Description of the optional features of the force field begins with the line defining the type of additional potential features. These are:
describes torsion angles in terms of MM3 potential:
The first line of this section contains the number of torsions of this type followed by lines in which fields 1)-4) define atoms and fields 5)-7) constants and in for each torsion angle of this type.
describes torsion angles given by the Ryckaert-Bellemans potential:
The first line of this section contains the number of torsions of this type followed by lines in which fields 1)-4) define atoms and fields 5)-9) constants in for each torsion angle of this type.
improper dihedral potential:
field 5) is the equilibrium angle in degrees and 6) is the force constant
introduces a list, over-reading Lennard-Jones parameters for 1-4 interactions for the specified atoms. This list consists of the following:
the first line - number of atoms in the list;
other lines: the first field defines atom, the second is (Å) and the third parameter is in .
Scaling parameter for 1-4 LJ interactions, eventually specified by
slj14 keyword (see below), is applied to these modified LJ parameters
Scale 1-4 electrostatic interactions by this factor
Scale 1-4 Lennard-Jones interactions by this factor. This applies also to
LJ parameters modified by keywords
the .mmol file, and to parameters introduced by
of the input file.
Assign special LJ parameters for 1-4 neighbours
This parameter follows by a line specifying the number of special 1-4 pairs followed by the corresponding number of lines with four parameters: site numbers of the first and second atom, then LJ parameter (Å) and LJ parameter (kJ/mol).
Note: There are several ways to modify LJ parameters for 1-4 interactions. They are applied in the following order (each next definition overrides previous ones):
specialsection of the .mmol file) are applied
par14section of the .mmol file are applied
Pair_listkeyword of the input file is applied
slj14keyword for the corresponding molecular type
This parameter is exclusively for the flexible SPC model. It tells to the program to compute water intramolecular potential according to the paper by Toukan and Rahman, Phys. Rev. B, 31(2) 2643 (1985)
.mmol files are included into
For big molecules, procedure of writing
.mmol files may be
somewhat automatized by the utility