foam-extend4.1-coherent-io/tutorials/discreteMethods/molecularDynamics/mdEquilibrationFoam/periodicCubeWater/system/potentialDict

/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | foam-extend: Open Source CFD                    |
|  \\    /   O peration     | Version:     4.0                                |
|   \\  /    A nd           | Web:         http://www.foam-extend.org         |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    object      potentials;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

// Subdictionaries specifying types of intermolecular potential.
// Sub-sub dictionaries specify the potentials themselves.

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Removal order

// This is the order in which to remove overlapping pairs if more than one
// type of molecule is present.  The most valuable molecule type is at the
// right hand end, the molecule that will be removed 1st is 1st on the list.
// Not all types need to be present, a molecule that is not present is
// automatically less valuable than any on the list.  For molecules of the
// same type there is no control over which is removed.

removalOrder ( water );

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Potential Energy Limit

// Maximum permissible pair energy allowed at startup.  Used to remove
// overlapping molecules created during preprocessing.

potentialEnergyLimit 1e-18;

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Pair potentials

// If a pair are not present here it is assumed that they do not interact.

// Electrostatic pair interactions are not listed here - they are handled
// separately.

// If there are r different type of molecules, and a pair force is required
// between all combinations, then there are C = r(r+1)/2 combinations,
// i.e. for r = {1,2,3,4}, C = {1,3,6,10} (sum of triangular numbers).

// Pair potentials are specified by the combinaition of their ids,
// for MOLA and MOLB, "MOLA-MOLB" OR "MOLB-MOLA" is acceptable
// (strictly OR, both or neither will throw an error)

pair
{
    O-O
    {
        pairPotential   lennardJones;
        rCut            1.0e-9;
        rMin            0.1e-9;
        dr              1e-13;
        lennardJonesCoeffs
        {
            sigma       3.154e-10;
            epsilon     1.07690722e-21;
        }
        energyScalingFunction   noScaling;
        writeTables     yes;
    }

    electrostatic
    {
        pairPotential   dampedCoulomb;
        rCut            1e-9;
        rMin            2e-11;
        dr              2e-12;
        dampedCoulombCoeffs
        {
            alpha       2e9;
        }
        energyScalingFunction   shiftedForce;
        writeTables     yes;
    }
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// Tethering Potentials

tether
{
    O
    {
        tetherPotential restrainedHarmonicSpring;
        restrainedHarmonicSpringCoeffs
        {
            springConstant  0.277;
            rR              1.2e-9;
        }
    }
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
// External Forces

// Bulk external forces (namely gravity) will be specified as forces rather
// than potentials to allow their direction to be controlled.

external
{
    gravity             (0 0 0);
}

// ************************************************************************* //