6.14. MD ‣ Gromacs menu

It is a menu about Gromacs.

Because Winmostar runs Gromacs on the Cygwin environment, in order to use this function, please set up CygwinWM is required.

6.14.1. Asign Force Field

Asign Force Field. The choices vary depending on the type of solver.

Automatically assign parameters

Assign new force field parameters.

(General)

Specify the force field for molecules other than proteins and water molecules. In the case of GAFF, GAFF2 or OPLS/AA-+GAFF, acpype is used, in the case of Dreiding, an in-house program is used, and in the case of UFF, modified OpenBabel is used. The setting of Dreiding is written in: file: polymer/dreiding.lib.txt. See Universal Force Field for more information about UFF.

Exception: For specific molecules, assign the user specified LJ parameters without using the force field selected in (General). In the left column of the subwindow, check the molecule you want to specify the LJ parameter and enter the LJ parameter in the right column.

Note

For example, when you want to allocate LJ parameters to solid phase atoms in a solid-liquid interface system.

(Protein/Ion)

Specify the force field of the protein. At this point, atoms assigned amino acid residue names in PDB and gro format are recognized as proteins. Internally gmx pdb2gmx is used. CygwinWM $GMXDATA/top/amber03.ff/ions.itp is used to determine if it is an ion residue name.

Warning

This function can not be used when reading the molecular structure from a file not including residue name.

(Water)

Specify the force field of the water molecule. You must specify the selected water model with Solvate/Build Cell. Internally we get the parameters from the library of Gromacs topology installed in Cygwin.

Add [position_restraints] for protein

If a protein exists, write information ([position_restraints] section) to constrain the position in the topology file with -POSRES on the Advanced tab. Ignored if protein is absent.

Add [position_restraints] for protein

For the molecule specified by the user, write information ([position_restraints] section) to constrain the position in the topology file with -POSRES on the Advanced tab. For example, when fixing solid phase in solid-liquid interface system.

Add [distance/angle/dihedral_restraints] for selected atoms

For the molecule specified by the user, write information to constrain distance, angle, dihedral angle to topology file by -POSRES on the Advanced tab.

Dump Now

Based on the current settings, generate a topology file.

Note

If you want to customize the forcefield information by editing it with a text editor, first save the file containing the forcefield information using Dump Now and edit the top for Gromacs or the data file for LAMMPS with a text editor.
Next, for Gromacs, import the gro file at File ‣ Import File (select Discard and import), then at Assign Force Field select :guilabel:` Select Use parameters written in topology file and click the OK button. You will then be asked for the location of the top file, so open the top file you just saved and edited.
For LAMMPS, import the data file at File ‣ Import File (select Discard and import), then at Assign Force Field, select Use the parameters written in file opened on :guilabel:`main window and click on the Next > button. If the force field information is not written in the data file, you will get a Choose the type of force field, choose the type of generic force field you want to use and click the OK button.
Charges are taken from the structure displayed in the main window. If more than one type of charge is set in the main window (for example, if the GAMESS log file is opened and Mulliken charge and Lowdin charge are set), the following order of priority is used: (high priority) User charge > NBO charge > Lowdin charge > ESP charge > Mulliken charge (low priority). When the file is opened and the Mulliken charge and Lowdin charge are set (for example, when the file is opened and the Mulliken charge and Lowdin charge are set), the order of priority is User charge > NBO charge > Lowdin charge > ESP charge > Mulliken charge (low priority).

Use parameters defined in external parameter file (for inorganic system, ReaxFF or DPD)

(For LAMMPS) Select when you want to use inorganic potential, ReaxFF or DPD. After pressing the Next > button, specify the type of force field to be actually used.

Use parameters written in topology file

(For Gromacs) Select to execute MD calculation using the existing top file. The corresponding gro file must be open in the main window.

Use parameters written in file opened on main window

(For LAMMPS) Select to execute MD calculation using the existing data file. The data file to be used must be open in the main window. After pressing the Next > button, specify the type of force field to use.

6.14.2. Workflow Setting

Set up and run the Gromacs calculation flow in project mode. 12-Step Compression in Preset is the polymer equilibration procedure described in [Hofmann2000_2] , [Larsen2011_2] . Also, 21-Step Compression-Decompression is the polymer equilibration procedure described in [Larsen2011_2].

Hofmann2000_2

Hofmann, L. Fritz, J. Ulbrich, C. Schepers and M. Bohning, Macromol. Theory Simul., 9 (6), (2000), 293–327.

Larsen2011_2(1,2)

G.S. Larsen, P. Lin, K.E. Hart and C.M. Colina, Macromolecules, 44 (17), (2011 ), 6944-6951.

Preset
Loads and saves a preset of settings.

# of Jobs
Specifies the number of jobs.

Enable parameter/structure scan
This feature requires the purchase of an add-on. It allows you to run multiple calculations where only certain parameters differ (parameter scan) or to run calculations with the same parameters for multiple structures (structure scan).

Click Config to open the configuration window for the scan calculation. For parameter scans, select %WM_SCAN1% for the Target Variable and enter the parameters you wish to set for %WM_SCAN1% in each row of the Values. Then, enter %WM_SCAN1% in the parameters you want to set in the Workflow Settings window or Keyword Settings window. For structure scan, select %WM_STRUCT% for Target Variable when the animation appears in the molecule display area (e.g., by opening an SDF file).

Import
Import the settings output by Export. Click the arrow to the right of the button to recall settings previously used in the same project or on Winmostar.

Export
Output configuration file.

OK
Run a calculation or generate a file with your settings. See For project mode for details.

Details
Set up detailed calculation conditions. The Configure will be launched.

Ensemble
Specifies the ensemble type. However, tcoupl is forced to nose-hoover when Precision, Medium is High.

Configuration

Minimize

integrator=steep

tcoupl=no

pcoupl=no

Minimize(NMA)

integrator=l-bfgs

tcoupl=no

pcoupl=no

emtol=0.01

-DFLEXIBLE=True

NVT

integrator=md

tcoupl=berendsen

pcoupl=no

NPT

integrator=md

tcoupl=berendsen

pcoupl=parrinello-rahman

pcoupltype=isotropic

NPT(aniso)

integrator=md

tcoupl=berendsen

pcoupl=parrinello-rahman

pcoupltype=anisotropic

NPT(z)

integrator=md

tcoupl=berendsen

pcoupl=parrinello-rahman

pcoupltype=semiisotropic

NVE

integrator=md

tcoupl=no

pcoupl=no

NPH

integrator=md

tcoupl=no

pcoupl=parrinello-rahman

pcoupltype=isotropic

NPH(z)

integrator=md

tcoupl=no

pcoupl=parrinello-rahman

pcoupltype=semiisotropic

NPT+Rescale Cell

integrator=md

tcoupl=berendsen

pcoupl=parrinello-rahman

pcoupltype=isotropic

Rescale box=True

NVE+Rescale Vel

integrator=md

tcoupl=none

pcoupl=none

Rescale velocities=True

NMA

integrator=nm

Ext from full-prec traj=True

-DFLEXIBLE=True

Temperature
Specify temperature.

Pressure
Specify pressure.

Simulation time
Specify simulation time.

# of snapshots
Specify the number of times to output coordinates and velocity to the trr file.

Initial velocity
If Random, the first speed is generated randomly. if From parent, the last speed of the previous job is inherited.

Free boundary condition
Calculate with free boundaries instead of periodic boundary conditions.

Configuration

True

pbc=no

coulombtype=cut-off

nstlist=1

ns-type=simple

cutoff-scheme=group

Use buffer-tolerance=False

comm-mode=angular

False

pbc=xyz

coulombtype=pme

nstlist=10

ns-type=grid

cutoff-scheme=verlet

Use buffer-tolerance=True

comm-mode=linear

Precision
Sets the precision of the calculation. However, constraints is forced to hbonds when Ensemble is Minimize and none when Minimize(NMA) or NMA.

Configuration

Low

Modify cutoff=True

rvdw=1

rvdw-switch=0.9

rcoulomb=1

rcoulomb-switch=0.9

nstenergy=10

dt=0.002

nhchainlen=10

shake-tol=1e-5

pme-order=4

ewald-rtol=1e-6

fourier-spacing=0.12

vdw-modifier=potential-shift-verlet

coulomb-modifier=potential-shift-verlet

nsttcouple=-1

nstpcouple=-1

Enable double precision=False

nstcomm=50

lincs-order=4

lincs-iter=1

buffer-tolerance=1e-6

constraints=all-bonds

Medium

Modify cutoff=True

rvdw=1.2

rvdw-switch=1.1

rcoulomb=1.2

rcoulomb-switch=1.1

nstenergy=20

dt=0.001

nhchainlen=10

shake-tol=1e-6

pme-order=4

ewald-rtol=1e-6

fourier-spacing=0.11

vdw-modifier=potential-shift-verlet

coulomb-modifier=potential-shift-verlet

nsttcouple=-1

nstpcouple=-1

Enable double precision=True

nstcomm=50

lincs-order=4

lincs-iter=1

buffer-tolerance=1e-6

constraints=hbonds

High

Modify cutoff=True

rvdw=1.5

rvdw-switch=1.4

rcoulomb=1.5

rcoulomb-switch=1.4

nstenergy=40

dt=0.0005

nhchainlen=1

shake-tol=1e-9

pme-order=6

ewald-rtol=1e-9

fourier-spacing=0.10

vdw-modifier=none

coulomb-modifier=none

nsttcouple=-1

nstpcouple=-1

Enable double precision=True

nstcomm=1

lincs-order=8

lincs-iter=2

buffer-tolerance=1e-9

constraints=hbonds

6.14.3. Configure

Set calculation conditions of Gromacs. To set up the calculations immediately after setting Run button, once to return to the main window please press OK button.

See Run Gromacs for the behavior when clicking Run.

Assign Charges Automatically will start automatically if there is a molecule to which no charge is assigned. If no force field is assigned, Asign Force Field will be launched automatically.

Reset button returns to the default state. Save the setting excluding Force Field with Save button. Load the setting saved with Save with the Load button.

Continue Simulation
Execute a continuous job.

For details, see Run Gromacs.

Preset
Specify the preset of the calculation condition. Each preset changes the following keywords.

Minimize

(fast)

NVT

(fast)

NPT

(fast)

NVE

(fast)

dt

0.002

0.002

0.002

nsteps

5000

5000

5000

5000

integrator

steep

md

md

md

gen-vel

yes

no

no

tcoupl

berendsen

berendsen

ref-t

300

300

pcoupl

no

parrinello-rahman

ref-p

1,0

pbc

yes

yes

yes

yes

comm-mode

linear

linear

linear

linear

nstcomm

50

50

50

nh-chain-length

10

10

nsttcouple

-1

-1

nstpcouple

-1

constraints

hbonds

all-bonds

all-bonds

all-bonds

lincs-order

4

4

4

lincs-iter

1

1

1

shake-tol

1e-5

1e-5

1e-5

nstxout

100

100

100

100

nstvout

100

100

100

100

nstenergy

10

10

10

10

buffer-tolerance

5e-3

5e-3

5e-3

5e-3

rvdw

1,0

1,0

1,0

1,0

rvdw-switch

0.9

0.9

0.9

0.9

coulombtype

pme

pme

pme

pme

rcoulomb

1,0

1,0

1,0

1,0

rcoulomb-switch

0.9

0.9

0.9

0.9

fourier-spacing

0.12

0.12

0.12

0.12

pme-order

4

4

4

4

ewald-rtol

1e-5

1e-5

1e-5

1e-5

Enable

double precision

False

False

False

False

-DFLEXIBLE

False

False

False

False

Extend simulation

from full-

precision

trajectory

False

False

False

False

Minimize

(medium)

NVT

(medium)

NPT

(medium)

NVE

(medium)

dt

0.001

0.001

0.001

nsteps

10000

10000

10000

10000

integrator

steep

md

md

md

gen-vel

yes

no

no

tcoupl

berendsen

berendsen

ref-t

300

300

pcoupl

no

parrinello-rahman

ref-p

1,0

pbc

yes

yes

yes

yes

comm-mode

linear

linear

linear

linear

nstcomm

50

50

50

nh-chain-length

10

10

nsttcouple

-1

-1

nstpcouple

-1

constraints

hbonds

hbonds

hbonds

hbonds

lincs-order

4

4

4

lincs-iter

1

1

1

shake-tol

1e-5

1e-5

1e-5

nstxout

200

200

200

200

nstvout

200

200

200

200

nstenergy

20

20

20

20

buffer-tolerance

1e-6

1e-6

1e-6

1e-6

rvdw

1.2

1.2

1.2

1.2

rvdw-switch

1.1

1.1

1.1

1.1

coulombtype

pme

pme

pme

pme

rcoulomb

1.2

1.2

1.2

1.2

rcoulomb-switch

1.1

1.1

1.1

1.1

fourier-spacing

0.11

0.11

0.11

0.11

pme-order

4

4

4

4

ewald-rtol

1e-6

1e-6

1e-6

1e-6

Enable

double precision

True

True

True

True

-DFLEXIBLE

False

False

False

False

Extend simulation

from full-

precision

trajectory

False

False

False

False

Minimize

NVT

NPT

NVE

dt

0.0005

0.0005

0.0005

nsteps

20000

20000

20000

20000

integrator

steep

md

md

md

gen-vel

yes

no

no

tcoupl

nose-hoover

nose-hoover

ref-t

300

300

pcoupl

no

parrinello-rahman

ref-p

1,0

pbc

yes

yes

yes

yes

comm-mode

linear

linear

linear

linear

nstcomm

1

1

1

nh-chain-length

1

1

nsttcouple

1

1

nstpcouple

1

constraints

hbonds

hbonds

hbonds

hbonds

lincs-order

8

8

8

lincs-iter

2

2

2

shake-tol

1e-9

1e-9

1e-9

nstxout

400

400

400

400

nstvout

400

400

400

400

nstenergy

40

40

40

40

buffer-tolerance

1e-9

1e-9

1e-9

1e-9

rvdw

1.5

1.5

1.5

1.5

rvdw-switch

1.4

1.4

1.4

1.4

coulombtype

pme

pme

pme

pme

rcoulomb

1.5

1.5

1.5

1.5

rcoulomb-switch

1.4

1.4

1.4

1.4

fourier-spacing

0.10

0.10

0.10

0.10

pme-order

6

6

6

6

ewald-rtol

1e-9

1e-9

1e-9

1e-9

Enable

double precision

True

True

True

True

-DFLEXIBLE

False

False

False

False

Extend simulation

from full-

precision

trajectory

False

False

False

False

Minimize

(vapor,fast)

NVT

(vapor,fast)

NPT

(vapor,fast)

NVE

(vapor,fast)

dt

0.002

0.002

0.002

nsteps

5000

5000

5000

5000

integrator

steep

md

md

md

gen-vel

yes

no

no

tcoupl

berendsen

berendsen

ref-t

300

300

pcoupl

no

parrinello-rahman

ref-p

1,0

pbc

no

no

no

no

comm-mode

angular

angular

angular

angular

nstcomm

50

50

50

nh-chain-length

10

10

nsttcouple

-1

-1

nstpcouple

-1

constraints

hbonds

all-bonds

all-bonds

all-bonds

lincs-order

4

4

4

lincs-iter

1

1

1

shake-tol

1e-5

1e-5

1e-5

nstxout

100

100

100

100

nstvout

100

100

100

100

nstenergy

10

10

10

10

buffer-tolerance

5e-3

5e-3

5e-3

5e-3

rvdw

1,0

1,0

1,0

1,0

rvdw-switch

0.9

0.9

0.9

0.9

coulombtype

cut-off

cut-off

cut-off

cut-off

rcoulomb

1,0

1,0

1,0

1,0

rcoulomb-switch

0.9

0.9

0.9

0.9

fourier-spacing

pme-order

ewald-rtol

Enable

double precision

False

False

False

False

-DFLEXIBLE

False

False

False

False

Extend simulation

from full-

precision

trajectory

False

False

False

False

Minimize

(vapor)

NVT

(vapor)

NPT

(vapor)

NVE

(vapor)

dt

0.0005

0.0005

0.0005

nsteps

20000

20000

20000

20000

integrator

steep

md

md

md

gen-vel

yes

no

no

tcoupl

nose-hoover

nose-hoover

ref-t

300

300

pcoupl

no

parrinello-rahman

ref-p

1,0

pbc

no

no

no

no

comm-mode

angular

angular

angular

angular

nstcomm

1

1

1

nh-chain-length

1

1

nsttcouple

1

1

nstpcouple

1

constraints

hbonds

hbonds

hbonds

hbonds

lincs-order

8

8

8

lincs-iter

2

2

2

shake-tol

1e-9

1e-9

1e-9

nstxout

400

400

400

400

nstvout

400

400

400

400

nstenergy

40

40

40

40

buffer-tolerance

1e-9

1e-9

1e-9

1e-9

rvdw

1.5

1.5

1.5

1.5

rvdw-switch

1.4

1.4

1.4

1.4

coulombtype

cut-off

cut-off

cut-off

cut-off

rcoulomb

1.5

1.5

1.5

1.5

rcoulomb-switch

1.4

1.4

1.4

1.4

fourier-spacing

pme-order

ewald-rtol

Enable

double precision

True

True

True

True

-DFLEXIBLE

False

False

False

False

Extend simulation

from full-

precision

trajectory

False

False

False

False

Minimize

(NMA)

NMA

dt

nsteps

20000

20000

integrator

l-bfgs

nm

gen-vel

tcoupl

ref-t

pcoupl

ref-p

pbc

yes

yes

comm-mode

nstcomm

nh-chain-length

nsttcouple

nstpcouple

constraints

none

none

lincs-order

lincs-iter

shake-tol

nstxout

400

400

nstvout

400

400

nstenergy

40

40

buffer-tolerance

1e-9

1e-9

rvdw

1.5

1.5

rvdw-switch

1.4

1.4

coulombtype

pme

pme

rcoulomb

1.5

1.5

rcoulomb-switch

1.4

1.4

fourier-spacing

0.10

0.10

pme-order

6

6

ewald-rtol

1e-9

1e-9

Enable

double precision

True

True

emtol

0.01

-DFLEXIBLE

True

True

Extend simulation

from full-

precision

trajectory

False

True

# of Threads
Specify the thread parallel number.

MPI (for Remote Job)
Specify MPI parallel number. It is reflected only when executing by remote job submission.

Basic

Run Control

dt
Specify one step increment in numerical integration.

nsteps
Specify the maximum number of steps to calculate.

integrator
Specify the calculation algorithm.

Velocity Generation

gen-vel
Specify whether to generate the initial speed.

Fix random seed
When checked, gen-seed will be used.

gen-seed
Specify the initial speed random seed.

Explicitly set gen-temp
If checked, I will do the initial speed temperature here. If you do not enter ref - t will be the initial speed temperature.

Temperature Coupling

tcoupl
Select the temperature control algorithm.

tc-grps
Specify the group to be temperature controlled (more than one can be set with a space delimiter).

ref-t
Specify the set temperature (Multiple settings can be set with a space delimiter).

year-t
Specify the time constant for temperature control (more than one can be set with a space delimiter).

Pressure Coupling

pcoupl
Select pressure control algorithm.

pcoupltype
It shows how to move cells in pressure control.

ref-p
Specify set pressure.

year-p
Specify the time constant for pressure control.

compressibility
Specify the compression ratio of the whole system.

Advanced

Boundary Condition

pbc
Select the periodic boundary condition.

Energy Minimization

emtol
Specify the maximum force which is the convergence condition of energy minimization calculation.

emstep
Specify the initial value of step width to move particles in energy minimization calculation.

Run Control

comm-mode
Specify how to remove the momentum of the whole system.

nstcomm
Specify the frequency of removing the momentum of the whole system.

Temperature/Pressure Coupling

nh-chain-length
Specify the number of stages of Nose-Hoover chain when temperature is controlled by the Nose-Hoover method.

nsttcouple
Specify the frequency of temperature control.

nstpcouple
Specify the frequency of temperature control.

refcoord-scaling
Specify the scaling of the reference coordinates of position restraint during temperature control.

Constraints

constraints
Select the constraint condition.

constraint-algorithm
Select the constraint algorithm.

continuation
Specify whether to inherit the constraint distance from the parent job.

lincs-order
Specify the order of the LINCS method.

lincs-iter
Specify the number of iterations in the LINCS method.

shake-tol
Specify the truncation error parameter used for the convergence judgment of the SHAKE method.

Misc.

print-nose-hoover-chain-variables
Specify this parameter when transferring temperature/pressure control parameters to a child job.

define -DFLEXIBLE
Select to make water molecule flexible.

define -DPOSRES
Select this to constrain the position of a specific molecule. (Include posres.itp)

Extend simulation from full-precision trajectory
If this item is checked and Continue Simulation is checked, the job is continued from the trr file of the previous job. If this item is not checked, the job is continued from the gro file in the final state of the previous job. For example, if you want to run normal mode analysis after the energy minimization calculation, you need to check the box.

Output

Output Control

nstxout
Specify the frequency of atomic coordinates output in steps.

nstvout
Specify the frequency of atomic velocity output in steps.

nstenergy
Specify the frequency of outputting system-wide statistics such as energy to edr file (energy file) in steps.

nstxout-compressed
Specify the frequency of atomic coordinates output in xtc format which can save file size by the step number.

compressed-x-grps
Specify the group to output in xtc format. By default, the entire system is targeted.

Interaction

Modify cutoff radii not to exceed L/2
When checked, automatically adjusts rlist, rvdw, rvdw-switch, rcoulomb, and rcoulomb-switch so that they do not exceed half the lattice constant.

Neighbor Searching

nstlist
Specify how often to update the neighbor list.

ns-type
Specify how to create the neighbor list.

cutoff-shceme
Specify the method of selecting atoms to be included in the neighbor list.

Use buffer-tolerance
Specify the truncation error of binary potential energy, which is a parameter for automatically setting the cutoff distance of the neighbor list. When unchecked, the value of rlist is set as the cutoff distance.

rlist
Specify the cutoff distance of the neighbor list.

VdW

vdwtype
Specify the calculation method of van der Waals potential.

rvdw-switch
When Switching is selected for Van der Waals potential calculation, specify the distance at which Switching starts.

rvdw
Specify the cutoff distance of van der Waals potential calculation.

DispCorr
Select whether long-distance correction of energy and pressure accompany cutoff.

vdw-change
Select settings such as Switching/Shift when Van der Waals potential cutoff.

Electrostatics

coulombtype
Specify the calculation method of coulomb potential.

rcoulomb-switch
When Switching is selected for Coulomb Potential Calculation, specify the distance at which Switching starts.

rcoulomb
Specify the real space cutoff distance of Coulomb potential calculation.

Coulomb-change
Select the setting such as Switching/Shift at the cutoff of Coulomb potential.

Ewald

Set # of grids for fourier space
If checked, use fourier-spacing. If you do not want to use it, use fourier-nx, ny, nz.

fourier-spacing
Ewald, PME or PPPM method in wave number space mesh size.

fourier-nx, ny, nz
Ewald, PME or PPPM method to specify the cutoff distance or mesh number (x, y, z component, respectively) of wave number space.

pme-order
Specifies the order of the extrapolation function in the PME method.

ewald-rtol
Ewald, PME or PPPM method accuracy parameters.

Other

Other Parameters
Specify other settings based on the description of the mdp file.

Automatic

Rescale velocities to..
Use it when you want to bring the system temperature closer to the target temperature in the NVE ensemble. Calculate the scaling factor from the average temperature under calculation and the temperature entered here and scale the velocity of each particle in the final structure.

Rescale box size to..
It is used when calculating with the NVE or NVT ensemble in the state close to the set pressure after calculating with the NPT ensemble. Scale the final structure to the average cell size under calculation.

Options

Restore Working Folder
Click to return working folder to its pre-execution status, such as when a continuous job ends abnormally.

Dump .mdp File
Create and save a Gromacs calculation condition (mdp) file with the settings in the currently opened window.

Dump All Files for Remote
This function does not run Gromacs, but only saves the files needed for Gromacs calculations. Please open the Tools ‣ Remote Job Submission window before using this function.

Rerun from xtc
For the structure of the trajectory (xtc) file output from a calculation that has already been completed, only the energy is calculated using the calculation conditions set in the currently opened window, and the energy (edr) file is obtained.

Open top file
Open the top file generated by the Assign Force Field function in a text editor.

maxwarn
Allow continuation of calculation warning message Specify the maximum number of messages (0: suspend with one or more messages)

Verbose Output
Specify this when displaying the step under calculation.

Concatenate .edr and .trr files
Click to merge with the executed .edr file and .trr file. File binding is performed as postprocessing of Continue Simulation.

Unwrap Atoms (trjconv -pbc nojump)
Output the calculated .gro and .trr files at coordinates that do not wrap around at periodic boundaries (unwrapped).

Enable Double Precision
Execute MD calculation and pre-post processing with double precision version of Gromacs binary.

Overwrites any output file without making a backup in working folder
If checked, when creating a new file in the working folder, a backup will be made if there is an old file with the same name. To save disk space, it is recommended to uncheck this item if Make a Backup of Working Folder is checked.

Enable detailed parallelization setting
Instead of using -nt to specify the number of total threads, the number of parallel Thread-MPI (-ntmpi) and OpenMP (-ntomp) threads can be specified individually.

# of Thread-MPI
Specifies the number of Thread-MPI parallel number.

# of OpenMP
Specifies the number of OpenMP parallel number.

Reset
Reset settings..

Import
Loading configuration file.

Export
Output configuration file.

6.14.4. Run Gromacs

Run Gromacs. The execution method differs depending on the situation.

(Default) If Continue Simulation is unchecked and Automatically assign parameters is checked on Asign Force Field
Create a new coordinate file (extension: gro) and topology file (extension: top) before starting the job.

If Continue Simulation is unchecked and :guilabel:` Use parameters from topology file` is selected for Asign Force Field
Start the job using the coordinate file (extension: gro) opened in the main window and the topology file (extension: top) specified at Asign Force Field.

When Continue Simulation is checked
The coordinate file ( gmx_mdrun_tmp.gro) and the topology file ( gmx_tmp.top) in the working folder linked to the coordinate file (extension: gro) ) To start the job.

Following file will be generated with execution. As an example, the file/folder name when the input file is water.gro is also shown.

type

Description

out file

water.out

water.sh standard output text file.

sh file

water.sh

For running Gromacs and its pre/post processing

Shell script.

bat file

water.gro.bat

This is a batch file for executing water.sh.

Working Folder

water_gmx_tmp\

Working folder.

The following files are generated in the working folder. Only the main files are shown here.

type

Description

input.gro

In the case of a new job, the gro file specified at the time of execution is

copied.

In case of continuous job, it becomes the file of the previous job.

gmx_tmp.top

In the case of a new job, the top file specified at the time of execution is

copied.

In case of continuous job, it becomes the file of the previous job.

gmx_tmp.mdp

It is a file that specifies calculation conditions.

gmx_tmp_mdrun.tpr

Generate from gro, top, mdp file

It is an input file of mdrun.

gmx_tmp_mdrun.ndx

Index file for result processing.

gmx_tmp_mdrun.edr

Temperature, pressure, energy etc. were stored

It is an energy file.

gmx_tmp_mdrun.gro

It is a gro file of the final structure.

gmx_tmp_mdrun.trr

It is a trajectory file.

gmx_tmp_mdrun.xtc

Compressed trajectory file.

gmx_tmp_mdrun.log

This is the log file of mdrun.

Hint

** Working folder **

A working folder is a folder whose name is the name of the file opened in the main window plus a suffix.

** The suffix varies depending on the type of solver. **

For example, in the case of Gromacs, if the file opened in the main window is aaa.gro and the suffix is _ gmx_tmp, the working folder will be named aaa_gmx_tmp .

It must be in the same hierarchy as the file opened in the main window.

Processing continues in the working folder of the same name even when continuing jobs, but by default the backup of the working directory of the previous job is created just before the continuation job is executed.

The name of the backup will be the one with the smallest number in the range where duplicate names do not exist. For example, if the working folder is aaa_gmx_tmp, it is aaa_gmx_tmp1.

** Directories without numbers are always up to date. **

The job is run through Winmostar Job Manager.

6.14.5. Open Log File (log)

Open the log file (* _ gmx_tmp gmx_tmp_mdrun.log) of gmx mdrun with a text editor.

6.14.6. Open Stdout File

Open the standard output (*. Out) of the shell script when running Gromacs with a text editor.

6.14.7. Animation

Select the gro file and trr file, and animate the MD calculation trajectory.

The file name of the main window does not change.

For the animation display operation method, see Animation display area.

6.14.8. Energy Plot

Selects the Gromacs output edr file and displays graphs of various thermodynamic quantities, such as energy, temperature, and pressure. Internally, the command gmx energy is executed. Please refer to the manual of gmx energy for more detailed behavior.

Please see Energy Plot window for how to operate subwindow.

6.14.9. Import Last Coordinate (gro)

* _ gmx_tmp \ gmx_tmp_mdrun.gro.

When using this function, the file name of the main window does not change.

6.14.10. Configure Sequential Job

Configure settings for continuous execution of Gromacs. If you want to run with settings other than the presets, enter the calculation conditions you want to run in advance with Configure and save it in gmxset format with the Save button.

6.14.11. Run Sequential Job

Run Gromacs sequentially based on the contents of Configure Sequential Job.

6.14.12. Analyses

6.14.12.1. Radial Distribution Function

Select a trr, tpr or ndx file output by Gromacs and display the radial distribution function. Internally, the command gmx rdf is executed. Please check the manual of gmx rdf for more detailed behavior. Radial distribution functions are computed between Reference Group and Target Group.

Definition

Atom
Set the calculation target to atomic coordinates.

Center of geometry
Make the calculation target geometric mean coordinates of the molecule.

Center of mass
Make the calculation target the molecular centroid position.

Output

RDF
Calculate radial distribution function.

Cumulative Number RDF
Calculate the integrated coordination number.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.2. Diffusion Constant/Mean Square Displacement

Select the trr, tpr, and ndx files output by Gromacs and display the mean square displacement and self-diffusion coefficient. Internally, the :command gmx msd is executed. Please refer to the manual of gmx msd for more detailed behavior.

Diffusion Constant
Use the gmx msd command to display the self-diffusion coefficient calculated from the slope of the time-mean square displacement graph.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.3. Scattering Function

Select a trr, tpr or ndx file output by Gromacs and display the scattering function. Internally, the :command gmx saxs is executed. Please refer to the manual of gmx saxs for more detailed behavior.

Interval
Specify the interval at which to acquire the snapshot used to calculate the scattering function. Attention is necessary because enormous calculation is necessary if it is too small.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.4. Velocity Autocorr/Vibration Spectrum

Select the trr, tpr, and ndx files output by Gromacs to display the velocity correlation function and the vibration spectrum. Internally, the :command gmx velacc is executed. Please refer to the manual of gmx velacc for more detailed behavior.

Velocity Autocorrelation
Output speed correlation function.

Vibration Spectrum
Output vibration spectrum.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.5. Static Dielectric Constant

Select a trr, tpr or ndx file output by Gromacs to display the distribution and histogram of the relative permittivity or dipole moments. Internally, the :command gmx dipoles is executed. Please refer to the manual of gmx dipoles for more detailed behavior.

Dielectric constant
Plot the relative dielectric constant. The value of epsilon at the last time in the graph is the relative dielectric constant obtained from that calculation. The value is output below the graph.

Histogram of total dipole momen
Plot the distribution of dipole moments for molecules belonging to the Target Group.

Autocorrelation function of dipole moment
Plot the autocorrelation function of the dipole moments. The definition of a dipole moment is selected in Definition.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.6. Share Viscosity

Select the trr, tpr, ndx file output by Gromacs and display the viscosity. Internally, the :command gmx tcaf is executed. Please refer to the manual of gmx tcaf for more detailed behavior.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.7. Density Profile

Select a trr, tpr or ndx file output by Gromacs to display the density distribution. Internally, the :command gmx density is executed. Please refer to the manual of gmx density for more detailed behavior.

Group
The density distribution is output for the components that are checked here.

Axis
Specifies the direction in which the density distribution is calculated.

# of slices
Specify the number of points for the density distribution graph.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.8. Free Volume

Select a trr, tpr or ndx file output by Gromacs to display the density distribution. Internally, the :command gmx freevolume is executed. Please refer to the manual of gmx freevolume for more detailed behavior.

Radius of probe
Specify the radius of the virtual probe particles that are randomly inserted into the system when calculating the free volume.

# of probe insertions
Specify the number of virtual probe particle insertions.

Random seed
Specify a random seed to determine where to insert virtual probe particles.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.9. Hildebrand Solubility Parameter

Calculate the Hildebrand solubility parameter from the edr, gro file output by Gromacs. Calculation results of gas phase and liquid phase are required. Hildebrand The gmx energy command is executed to obtain the cohesion energy, density (specific volume) and compression rate necessary for calculating the solubility parameter.

6.14.12.10. Chi/DPD parameter

Calculate the Chi parameter · DPD aij parameter from the edr, gro file output by Gromacs. It is necessary to calculate the gas phase and liquid phase of each of the two components. Internally use the value calculated by Hildebrand Solubility Parameter.

6.14.12.11. Bond/Angle/Dihedral distribution

Select a trr, tpr, or ndx file output by Gromacs to display the distribution of distances, angles, or two-plane angles between the selected groups. Internally, the gmx distance command (distance) or the gmx angle command (angle, two plane angle) is executed. Please refer to the manuals of gmx distance and gmx angle for more detailed behavior.

vdwtype
Select the type of value to plot (bond, angle, dihedral, improper or ryckaert-bellmemans).

Calculate for marked atoms
Calculates the distance, angle, or dihedral angle between atoms marked with a marker in the main window.

Calculate for target group
Calculate the distance, angle, or dihedral angle using the NDX file selected in the Target Group.

Calculate for
Calculates the angle or dihedral angle for the selected angletype or dihedraltype.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.12. Hydrogen bonding analysis

Selects the trr, tpr, and ndx files output by Gromacs and analyzes the hydrogen bonds between the selected groups. Internally, the gmx hbond command is executed. Please refer to the gmx hbond manual for detailed behavior.

vdwtype
Select the type of values to plot.

Cutoff angle
Specifies the cutoff value for the hydrogen-donor-acceptor angle when determining hydrogen bonding.

Cutoff distance
Specifies the cutoff value for the donor-acceptor distance when determining hydrogen bonding.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.13. Root Mean Square Deviation

Select the trr, tpr, and ndx files output by Gromacs and display the RMSD (mainly for proteins). Internally, the :command gmx rms is executed. Please refer to the manual of gmx rms for more detailed behavior.

Group
Results are output for the components checked here. Normally select Backbone.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.14. Radius of Gyration

Select a trr, tpr or ndx file output by Gromacs and display the rotation radius (mainly for the protein). Internally, the :command gmx gyrate is executed. Please refer to the manual of gmx gyrate for more detailed behavior.

Group
Results are output for the components checked here. Normally you will select Backbone.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.12.15. Ramachandran Plot

Select the trr, tpr, and ndx files output by Gromacs to display the Ramachandran plots for each amino acid residue. Internally, the :command gmx rama is executed. Please refer to the manual of gmx rama for more detailed behavior.

Residue
Here a Ramachandran plot of the selected residue is output.

Target Group
Calculate the physical quantity for molecules/atoms belonging to the selected group here. A group written in the opened ndx file can be selected here.

Reference Group
It only appears for physical quantities to be calculated for atom pairs such as radial distribution functions. The physical quantity is calculated between Target Group and Reference Group.

Create Group
Register a new group from the atom name written in the gro file.

To define atoms group selected in the main window as a group, use MD ‣ Gromacs ‣ Add Selected Group to Index File (ndx).

In the Create Group window, check Extracted Atom Names and enter New group Name and press the Create button, the group is added to the ndx file It will be added. When you press the Close button, the groups added to Target Group and Reference Group are added.

First Frame
Specify the start time when trajectory is read in ps units.

Last Frame
Specify the end time, in ps, to read trajectories. If Maximum is checked, the last frame is specified.

Draw
Execute the result analysis program and display the graph.

For how to operate the graph drawing area, see How to operate the graph.

6.14.13. Modify Trajectory File

You can perform operations such as thinning, rotation, and calculation of spatial distribution functions on the trajectory data in the trr or xtc file output from Gromacs. Internally, the :command gmx trjconv is executed. Please refer to the manual of gmx trjconv for more detailed behavior. Click Execute button to start the process.

Output interval
Specify how many frames to output by thinning the trajectory.

Postprocess
Specify the operation after processing. If Spatial distribution function is selected use gmx spatial.

Target group
Specify the group to output.

Rotate and Trans
The group specified by Reference group is fixed so that the group specified by Target group is rotated and translated.

Reference group
Specify refernce in Roate and Trans.

Group for SDF
Specify which group to calculate SDF calculated when Spatial distribution function (SDF) is selected in Postprocess.

6.14.14. Start ER

Calculate the solvation free energy using the energy indication (ER) method.

Execute the calculation of the following three in Gromacs beforehand and leave each working folder. Only use equilibrium state data after finishing equilibration such as energy minimization.

Solution system (1 solute molecule + many solvent molecules)

Solvent system (large number of solvent molecules)

Solute system (one solute molecule)

Drag and drop the working folder of A. Solution system on the Solution tab. Or, in each column of the xtc, log, top file, press … button to read individual files.

Likewise select the B. Solvent system file on the Solvent tab.

Similarly select the C. Solute system file in the Solute tab. If an xtc file is specified, if the solute specifies a flexible model, pdb or gro file, it is treated as a rigid body model.

Select the molecular name of the solute in Solute Name.

If necessary, specify MPI parallel number at free energy calculation from Options button.

To implement free energy calculation in the local environment press the Start button. Calculation begins when you specify the folder to output the result. On Cygwin, ermod flows.

To implement in the remote environment, press the Close button once. And at Remote job execute Program with ermod. On the remote server, it is necessary for ermod and slvfe command to pass $PATH. (Installing ERmod on remote server is here <https://winmostar.com/en/gmx4wm_en_linux.html>) After finishing the calculation, press get button in Remote job, you will find ermod_remote_* under the folder where winmostar.exe is placed and the result is transferred from the remote server.

After calculating the free energy calculation, to display the result, select the Import ER menu.

Hint

If you want to analyze the data using ERmod functions, which are not supported by Winmostar, you can also follow the procedure below.

First, we will use Winmostar to calculate the MD for solution, solvent only, and solute only. For those procedures, please refer to the tutorial on using the ER method.

Follow the steps after “Generate input configuration for running ermod” in Quick Start Guide on the official ERmod homepage. Follow the steps after “Generate input configuration for running ermod”. Click [Tools]-[Cygwin] in Winmostar to start the Cygwin terminal, where the installation of Gromacs, ERmod, etc. is completed. The “(ERmod directory)” in the procedure is /usr/local/ermod on Cygwin. The etohsolution.top will be the top file saved at the start of the solution calculation. Please use solution_run.xtc and solution_run.log which are stored in the working folder of MD for solution, solvent only, and solute only, respectively.

6.14.15. Import ER

The results processed by Start ER are displayed. After selection, specify the output destination folder specified by Start ER. You can specify units for displaying energy in Unit. Press the Log button to display ERmod’s log file.

6.14.16. Start BAR

Calculate the solvation free energy using the Bennett Acceptance Ratio (BAR) method.

Calculate the solution system (1 solute molecule plus a large number of solvent molecules) using Gromacs. Leave all working folders for each step of equilibration and calculation of equilibrium state.

Select Start BAR.

Specify how to integrate the state (lambda = 1, Full Coupling) in which the solute is not interacting with the solvent (lambda = 0) to the interaction state (lambda = 1, Full Coupling) on the Integration Path tab. Enter the coupling coefficient of van der Waals potential (left) and the coupling coefficient of coulomb potential (right) in the two columns on the left of the Insert button and press Insert to add an integration path.You can delete the integration route by pressing Delete.

In Procedure tab, specify the simulation procedure of each state on the integration path. Specify the procedure of equilibration of solution system (lambda = 1) prepared beforehand in folder unit. Add a folder by dragging and dropping to the Add button or list. Delete folder with Delete button. The calculations performed in the last step of the list are used for free energy calculations.

Press Start to execute MD calculation for each lambda.

After finishing MD calculation of each lambda, to display the result, choose Import BAR.

6.14.17. Import BAR

Display the result of processing with Start BAR. After selecting the menu, specify the destination folder with Start BAR.

The gmx bar is executed in the background and the result is displayed. Please refer to the manual of gmx bar for more detailed behavior.

Unit allows you to specify the unit in which the energy is displayed. If you press Log button, the log file of gmx bar will be displayed. The displayed graph shows the change in free energy between the state in which the solute is not interacting with the solvent (lambda=0) and the state in which it is interacting (lambda=1).