MM_TERMS


Function

MM_Terms contains a definition of the terms necessary for calculating the molecular mechanics energy of the system. It also has several procedures that manipulate this data.

This module and the data stored in it are discussed in chapters 4 and 5 of the book A Practical Introduction to the Simulation of Molecular Systems.

Dependencies

Module Variables
DEFINITIONS DP
IO_UNITS OUTPUT
ATOMS ATOM_NAME_LENGTH, NATOMS


Public Types

Three public data types are defined by this module.

Type Purpose
ANGLE_TERM Hold a bond angle term definition.
BOND_TERM Hold a bond term definition.
DIHEDRAL_TERM Hold a dihedral angle term definition.


ANGLE_TERM

Field Type Purpose
I Integer The number of the first atom in the angle.
J Integer The number of the second atom in the angle.
K Integer The number of the third atom in the angle.
EQ Real The equilibrium angle in radians.
FC Real The force constant.


BOND_TERM

Field Type Purpose
I Integer The number of the first atom in the bond.
J Integer The number of the second atom in the bond.
EQ Real The equilibrium distance.
FC Real The force constant.


DIHEDRAL_TERM

Field Type Purpose
I Integer The number of the first atom in the dihedral.
J Integer The number of the second atom in the dihedral.
K Integer The number of the third atom in the dihedral.
L Integer The number of the fourth atom in the dihedral.
PERIOD Integer The periodicity of the dihedral term.
FC Real The force constant.
PHASE Real The phase of the dihedral term.


Public Variables

There are a number of variables defined in the module. None are parameters.

Variable Type Size Purpose
ATMTYP Character ( Len = ATOM_NAME_LENGTH ) (1:NATOMS) The force field atom types.
NBONDS Integer Scalar The number of bonds in the system.
BONDS Bond_Term (1:NBONDS) The bond terms.
NANGLES Integer Scalar The number of bond angles in the system.
ANGLES Angle_Term (1:NANGLES) The bond angle terms.
NDIHEDRALS Integer Scalar The number of dihedral angles in the system.
DIHEDRALS Dihedral_Term (1:NDIHEDRALS) The dihedral angle terms.
NIMPROPERS Integer Scalar The number of improper dihedral angles in the system.
IMPROPERS Dihedral_Term (1:NIMPROPERS) The improper dihedral angle terms.
SCALE_EL14 Real Scalar The scaling factor for the electrostatic 1-4 interactions.
SCALE_LJ14 Real Scalar The scaling factor for the Lennard-Jones 1-4 interactions.
ATMEXCI Integer (1:NATOMS+1) The index array for the 1-2, 1-3 and 1-4 excluded interactions.
ATMEXCJ Integer (1:ATMEXCI(NATOMS+1)) The second atoms of the 1-2, 1-3 and 1-4 excluded interactions.
ATME14I Integer (1:NATOMS+1) The index array for the 1-4 non-bonding interactions.
ATME14J Integer (1:ATME14I(NATOMS+1)) The second atoms of the 1-4 non-bonding interactions.
ATMCHG Real (1:NATOMS) The atomic charges.
ATMCHG14 Real (1:NATOMS) The atomic charges for 1-4 interactions.
ATMEPS Real (1:NATOMS) The Lennard-Jones well-depths for the atoms, E, stored as 2 E1/2.
ATMEPS14 Real (1:NATOMS) The Lennard-Jones well-depths for the 1-4 interactions stored in the same way as for ATMEPS.
ATMSIG Real (1:NATOMS) The Lennard-Jones radii for the atoms, S, stored as S1/2.




Public Procedures

There is a single subroutine that users may want to use from this module.

SubroutinePurpose
MM_TERMS_SUMMARY Print out a summary of the MM terms defined in the module.


MM_TERMS_SUMMARY

There are no arguments for this subroutine.



Stability

It may be that the atom data will be reorganized by defining an appropriate data type. Otherwise, stable.



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