2. In/Out Files¶

Author:	Kota Kasahara

2.1. Input Files¶

System configuration file (.cfg)
Simulation configuration file (.cfg)
Structure file (.pdb)
Initial coordinates and velocities file (.restart)
Topology file (.tpl)
Integrated binary (.cls)
SHAKE setting file (.shk)
V-McMD (or V-AUS) setting files (.inp, .vert)
V-AUS restart file (.dat)
Atom group definition file (.inp)
Distance restraint file (.inp)

2.1.1. System configuration file (.cfg)¶

The input file describing configurations about a simulation system. Other some input files are specified in this file, and they are integrated into the integrated binary file (.cls) by using mdinput_generator.py program. In the configuration file, a set of a key and value(s) is specified in each line.

--fn-i-tpl
md.tpl
- The file name of the topology file (.tpl).
--fn-i-initial-pdb

md.pdb
- The file name of the structure file (.pdb).
--fn-i-restart
md.restart
- The file name of the initial coordinates and velocities file (.restart)
--cell-x
61.2425
--cell-y
61.2425
--cell-z
61.2425
- The lengths of the periodic boundary cell in each axis in angestrome unit.
--fn-i-shake
system.shk
- The file name of the shake setting file.
--fn-i-ttp-v-mcmd-inp

ttp_v_mcmd.inp
--fn-i-ttp-v-mcmd-initial

start.vert
- The file name of the V-McMD setting files.
--fn-i-atom-group

atom_groups.inp
- The file name of the atom group definition file.
--fn-i-dist-restraint

dist_rest.inp
- The file name of the distance restraint setting file.
--fn-i-aus-restart

aus_rest.dat

2.1.2. Simulation configuration file (.cfg)¶

The input file describing configurations about simulation conditions.

2.1.2.1. Common configurations¶

--mode
md
- Only the keyword “md” is valid.
--gpu-device-id

0
- The device ID of GPGPU board to be used.
--integrator
leapfrog-presto
- Type of integrator
- leapfrog-presto * The leap frog algorithm. * For NVE, NVT (rescaling), SHAKE
- zhang * The integrator by Zhang [Zhang_1997] * For the Hoover-Evans thermostat (“hoover-evans”) * SHAKE cannot be applied.
--thermostat
scaling
- none * NVE
- scaling * Scaling velocities.
- hoover-evans * Hoover-Evans. This can be applied for the integrator “zhang”.
--cutoff
12.0
- The cutoff length for non-bonded potential (angestrome unit)
--n-steps
10
- The number of steps of the simulation.
--time-step
2.0
- The integration time step
--electrostatic

zero-dipole
- “zero-dipole” * The Zero-dipole summation (ZD) method developed by Fukuda [Fukuda_2011] .
- “zero-quadrupole”
- “zero-octupole”
- “zero-hexadecapole” * The Zero-multipole summation (ZM) method developed by Fukuda [Fukuda_2014] .
- For GPU mode, only zero-dipole with –ele-alpha 0.0 is acceptable.
--ele-alpha
0.0
- The dumping factor fo ZM method.
- For GPU mode, only 0.0 is acceptable
--temperature
300
- Temperature for the thermostat.
–temperature-init * The initial temperature. Default value is the temperature specified by “–temperature” setting. * With this setting, “–heating-steps” should be set.
–heating-steps * The temperature is linearly increased or decreased from the –temperature-init to –temperature during the steps specified in this setting.
--print-interval-log

1
- Output interval for the log (the standard output)
--print-interval-coord

1
- Output interval for the trajectory file.
--fn-o-coord
et1.trr
- Output file name for the trajectory file.
--format-o-coord

gromacs
- The file format of the trajectory.
- presto
- gromacs * (!) The little endian
--fn-o-restart
md.restart
- Output restart file name.

--nsgrid-cutoff

13.0
- The cutoff length for the neighbor search (angestrome unit).
--nsgrid-update-intvl

10
- The interval steps for execution of the neighbor search.
--com-motion
cancel
- Settings for canceling the center of mass
- none
- cancel * Translation of the center of mass for some specified groups are cancelled. * The groups should be specified in “–com-cancel-group-name”
--com-cancel-group-name

grpA
- The name of an atom group COM motions of which to be cancelled.
- Multiple values can be specified.

2.1.2.2. Configuration for restraints¶

–dist-restraint harmonic * Functions for distance restraints * none * harmonic
–dist-restraint-weight * Scaling coefficient for the distance restraints

2.1.2.3. Configuration for the extended ensemble methods¶

--extended-ensemble

v-mcmd
- none * Extended ensemble is not used
- v-mcmd * The TTP-V-McMD method [Higo et al. (2013)]_
- v-aus * The TTP-V-AUS method [Higo et al. (2015)]_
--fn-o-vmcmd-log

ttp_v_mcmd.out
- Output file name of a virtual-system trajecotry.
--fn-o-extended-lambda

mule.ene
- Output file name of a log of the lambda value.
--print-interval-extended-lambda

1
- Output interval for the log of the lambda value.
--format-o-extended-lambda

ascii
- File format of the log of the lambda value.
- ascii
- binary

#* –aus-type 3 # * Type of AUS reaction coordinate. # * 3 # * The reaction coordinate is defined as the distance between centers of mass of the groups. * –enhance-sigma

A parameter for the recovery force in V-AUS simulation.

A margin of the lambda value.

–enhance-recovery-coef

2.1.2.4. Initial coordinates and velocityies file (.restart)¶

This file is compatible for myPresto/Psygene restart file. For the first run, this file with random velocities can be generated by presto_generate_velocities.py scripts in the toolkit. At the end of a simulation, final coordinates and velocities will be output at the file specified by –fn-o-restart option.

2.1.2.5. Topology file (.tpl)¶

This file is compatible for myPresto/Psygene topology file. It can be prepared by using myPresto/TopolgeneX program.

–fn-i-tpl md.tpl

2.1.2.6. SHAKE setting file.¶

This file is compatible for myPresto/Psygene SHAKE file. It can be prepared by using SHAKEinp program.

It should be specified in the system configuration file:

–fn-i-shake system.shk

2.1.2.7. V-McMD (or V-AUS) setting files (.inp, .vert)¶

These fiels are compatible for myPresto/Psygene files.

They should be specified in the system configuration file:

--fn-i-ttp-v-mcmd-inp

ttp_v_mcmd.inp
--fn-i-ttp-v-mcmd-initial

start.vert

2.1.2.8. V-AUS restart file (.dat)¶

This file is required for continuing a finished V-AUS job. It should be specified in the system configuration file:

–fn-i-aus-restart aus_rest.dat

At the end of a V-AUS job, this file is automatically generated at the file, specified by –fn-o-aus-restart option.

2.1.2.9. Atom group definition file (.inp)¶

This file defining groups of atoms. This informations are used for:

Canceling the center of mass motion
Defining enhaced groups for V-AUS simulations

In this ascii file, each line defines one atom group. The characters at the head of each line indicate the name of each group. Successive columns specify atoms in this group.

For example:

group1 1 4 6-9
group2 3 10-11 13

The group1 is composed of atoms 1, 4, 6, 7, 8, and 9. The group2 is composed of atoms 3, 10, 11, and 13.

The atom-ID are began from 1.

2.2. Output files¶

Standard output
Trajectory file (.cod)
Restart file (.restart)
V-McMD (or V-AUS) lambda trajectory
V-McMD (or V-AUS) virtual-system trajectory
V-AUS restart file

A simulation log will be output for the standard output. Redirection to a file is recommended.

The trajectory file format is compatible to myPresto/Psygene.

This file repeats the two pars: a header of the frame, and atomic coordinates at the frame.

For the header part:

[4 bytes, INT] The size of header parts in bytes. Always “44”.
[4 bytes, INT] Step number
[4 bytes, FLOAT] Time
[4 bytes, FLOAT] CPU time
[4 bytes, FLOAT] Total energy
[4 bytes, FLOAT] Kinetic energy
[4 bytes, FLOAT] Temperature
[4 bytes, FLOAT] Potential energy
[4 bytes, FLOAT] Always “0.0”
[4 bytes, FLOAT] Always “0.0”
[4 bytes, FLOAT] Always “0.0”
[4 bytes, FLOAT] Always “0.0”
[4 bytes, INT] The size of header parts in bytes. Always “44”.

For the coordinates part:

[4 bytes, INT] The size of this part. The nubmer of atom * 3 dimensions * 4 bytes.
[FLOAT] X, Y, and Z coordinates of each atoms.
[4 bytes, INT] The size of this part. The nubmer of atom * 3 dimensions * 4 bytes.

The restart file format is compatible to myPresto/Psygene.

This file is composed of the three pars: a header of the frame, atomic coordinates, and velocities.

For the header part:

[4 bytes, INT] The length of the following text. Alwasy “80”.
[80 bytes, CHAR] Description of this simulation (version information)
[4 bytes, INT] Alwasy “80”.
[4 bytes, INT] Alwasy “8”.
[4 bytes, INT] The number of atoms for coordinates.
[4 bytes, INT] The number of atoms for velocities.
[4 bytes, INT] Alwasy “8”.
[4 bytes, INT] Alwasy “36”.
[4 bytes, INT] Step number.
[4 bytes, FLOAT] Time.
[4 bytes, FLOAT] Total energy.
[4 bytes, FLOAT] Kinetic energy.
[4 bytes, FLOAT] Potential energy.
[4 bytes, INT] Alwasy “36”.

For the coordinates part:

[4 bytes, INT] The size of this part in bytes. The number of atoms * 3 dimenstions * 8 bytes.
[DOUBLE] X, Y, Z coordinates of each atom.
[4 bytes, INT] The size of this part in bytes. The number of atoms * 3 dimenstions * 8 bytes.

For the velocity part:

[4 bytes, INT] The size of this part in bytes. The number of atoms * 3 dimenstions * 8 bytes.
[DOUBLE] X, Y, Z velocities of each atom.
[4 bytes, INT] The size of this part in bytes. The number of atoms * 3 dimenstions * 8 bytes.

For V-McMD or V-AUS simulations, the lambda values are written on this file.

When –format-o-extended-lambda ascii is specified, a lambda value is recorded in each line of the ascii file.

When –format-o-extended-lambda binary, is specified, the values are dumped as a binary file.

[1-4 bytes] The magic number
[5-8 bytes] The precision (4 or 8)
[9-14 bytes] Always 1.
[After that] The lambda values

The trajectory of virtual-system coordinates is written as a two-columns, tab separated table.

The first column means the step number.
The second column means the virtual-system coordinate.

For example, in the case that virtual-system transitions are done in every 1000 steps,: