Compute hydration free energy using 3D-RISM with PC+ correction
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Python script to simplify computation of 3D-RISM pressure corrected (PC+/PC) hydration free energy. The 3D-RISM pressure is computed using the equation 20. from the following article:

Sergiievskyi, V.; Jeanmairet, G.; Levesque, M.; Borgis, D. Solvation Free-Energy Pressure Corrections in the Three Dimensional Reference Interaction Site Model. J. Chem. Phys. 2015, 143, 184116.

If you find the script useful please cite the following works:

Misin, M.; Fedorov, M.; Palmer, D. Hydration Free Energies of Ionic Species by Molecular Theory and Simulation, J. Phys. Chem. B. 2016.


Misin, M.; Fedorov, M. V.; Palmer, D. S. Accurate Hydration Free Energies at a Wide Range of Temperatures from 3D-RISM. J. Chem. Phys. 2015, 142, 091105.


Maksim Mišin

Usage examples

As an input script takes a pdb file with single solute. For example (methane.pdb):

ATOM      1  C1  MOL     1       3.537   1.423   0.000  1.00  0.00
ATOM      2  H1  MOL     1       4.089   2.224   0.496  1.00  0.00
ATOM      3  H2  MOL     1       4.222   0.611  -0.254  1.00  0.00
ATOM      4  H3  MOL     1       2.759   1.049   0.669  1.00  0.00
ATOM      5  H4  MOL     1       3.077   1.810  -0.912  1.00  0.00

1) 298.15 K methane hydration free energy calculation:

$ python methane.pdb
Starting SFE calculation for methane.pdb at T=298.15 K
Running AM1-BCC calculation...
Running 1D-RISM calculation...
Running 3D-RISM calculation...
Calculation has finished
RISM exchem=8.57636028 kcal/mol
PC+ dG*(hyd)=1.07928069898 kcal/mol
Detailed output can be found in methane_298.15/methane.log

2) 350 K calculation with tip3p water

$ python methane.pdb -t 350 --smodel TP3
Starting SFE calculation for methane.pdb at T=350.0 K
Running AM1-BCC calculation...
Running 1D-RISM calculation...
Running 3D-RISM calculation...
Calculation has finished
RISM exchem=9.01341914 kcal/mol
PC+ dG*(hyd)=1.35551076507 kcal/mol
Detailed output can be found in methane_350.0/methane.log

3) Using existing topology and susceptibility (xvv) files

$ python methane.pdb -p methane.prmtop -x water_nacl.xvv
Starting SFE calculation for methane.pdb at T=298.15 K
Reading user provided prmtop file
Using provided xvv file...
Running 3D-RISM calculation...
Calculation has finished
RISM exchem=8.67168499 kcal/mol
PC+ dG*(hyd)=1.1103088454 kcal/mol
Detailed output can be found in methane_298.15/methane.log


The script requires:

Get some help

$ python -h
usage: [-h] [-p PRMTOP] [--scale_chg SCALE_CHG] [-c MOLCHARGE]
                    [--multiplicity MULTIPLICITY] [--minimize MINIMIZE]
                    [-x XVV] [--smodel SMODEL] [--rism1d RISM1D]
                    [--closure [CLOSURE [CLOSURE ...]]] [-t TEMPERATURE]
                    [--clean_up CLEAN_UP] [--dir_name DIR_NAME]
                    [--timeout TIMEOUT]
                    [--tolerance [TOLERANCE [TOLERANCE ...]]] [--write_g]
                    [--write_c] [--write_u] [--write_asymp] [--noasympcorr]
                    [--buffer BUFFER] [--solvbox SOLVBOX SOLVBOX SOLVBOX]
                    [--grdsp GRDSP GRDSP GRDSP] [--polar_decomp]
                    [--verbose3d VERBOSE3D] [--maxstep3d MAXSTEP3D]

Run 3D-RISM single point calculation. This script is a wrapper around Amber
rism3d.snglpnt program, designed to simplify calculations. It also computes
pressure corrections to RISM solvation free energy.

optional arguments:
  -h, --help            show this help message and exit

Solute options:
  Options related to a solute molecule. Calculation requires only pdb and
  prmtop files. If prmtop file is not present, script will try to create
  this file using antechamber and tleap. By default AM1-BCC charges and GAFF
  will be used.

  molec.pdb             Input solute file. Must be in pdb format acceptable by
                        Antechamber. Must have a .pdb extension.
  -p PRMTOP, --prmtop PRMTOP
                        Path to parameters and topology (prmtop) file of
  --scale_chg SCALE_CHG
                        Scale all solute by this value prmtop file [1.0].
  -c MOLCHARGE, --molcharge MOLCHARGE
                        Charge of the solute [0].
  --multiplicity MULTIPLICITY
                        Multiplicity of the solute [1].
  --minimize MINIMIZE   Minimize solute before performing 3D-RISM calculation
                        using either gradient descent (min) or RISM
                        minimization using sander (rism, not recommended). If
                        no keywords are provided minimization is not

1D-RISM options:
  3D-RISM calculation requires xvv file (site-site susceptibilities) to run.
  If such file is not provided script can run a 1D-RISM to try to genrate
  it, but will asume that the solvent is pure water. Some of the 1D-RISM
  related options are in 3D-RISM group.

  -x XVV, --xvv XVV     Path to an existing xvv file. This will skip 1D-RISM
                        calculation and all related parameters will be
                        ignored. Solvent density as well as calculation
                        temeprature will be read from this file.
  --smodel SMODEL       Solvent model for 1D-RISM calculation available in
                        "$AMBERHOME/dat/rism1d/model/{smodel}.mdl" [SPC].
  --rism1d RISM1D       Type of 1D-RISM theory. Only DRISM has been
                        extensively tested [DRISM].

3D-RISM options:
  Options related to the main calculation.

  --closure [CLOSURE [CLOSURE ...]]
                        Brdige closure for 3D-RISM and 1D-RISM calculation if
                        it is necessary. Either HNC, KH, PSEn (n in PSEn
                        should be an integer) or a list of them for sequential
                        convergence. For 1D-RISM calculation only last closure
                        will be used [PSE3].
                        Temperature in K at which calculation will be
                        preformed. If xvv file was provided, this option will
                        be used only for naming directory [298.15].
  --clean_up CLEAN_UP   How should auxiliary files be treated: 0 - delete
                        nothing; 1 - delete some [default]; 2 - delete all but
                        input, results, and log.
  --dir_name DIR_NAME   Custom name for produced calculation directory. The
                        default one is: {mol_name}_{temperature}.
  --timeout TIMEOUT     Minutes after which 3D-RISM calculation will be
                        killed. Use 0 for no timeout. [0]. Only works on Unix-
                        like system.
  --tolerance [TOLERANCE [TOLERANCE ...]]
                        Maximum residual values for 3D-RISM solution
                        convergence. If many closures a list of closures can
                        be supplied [1E-5].
  --write_g             Write radial distribution functions produced in 3D-
                        RISM calculation.
  --write_c             Write direct correlation function produced in 3D-RISM
  --write_u             Write solute solvent potential energy grid.
  --write_asymp         Write asymptotics of total and direct correlation
                        fuctions in real space.
  --noasympcorr         Thermodynamics of 3D-RISM is calculated without long-
                        range asymptotics.
  --buffer BUFFER       Minimum distance between the solute and the edge of
                        the solvent box in A for 3D-RISM calculation [25].
                        Size of the x, y, and z dimensions of the box in
                        Angstroms. Specifying this parameter overrides buffer.
                        Linear grid spacings for x, y and z dimensions. Should
                        be separated with spaces. Units: A [0.5 0.5 0.5].
  --polar_decomp        Decomposes solvation free energy into polar and non-
                        polar components.
  --verbose3d VERBOSE3D
                        Verbosity of 3D-RISM calculation. 0 - print nothing; 1
                        - print iterations; 2 - print all [2].
  --maxstep3d MAXSTEP3D
                        Maximum number of iterations in 3D-RISM calculation


The script has been tested only on Ubuntu, but it should work on most Linux distributions and on Mac OS X. To make it Windows-friendly one would probably need to change the names of executable programs and add them to the PATH.