REACTION_PATH


Function

Reaction_Path has a procedure for generating a steepest-descent reaction path.

The use of this module fully explained in chapter 6 of the book A Practical Introduction to the Simulation of Molecular Systems.

Dependencies

Module Variables
DEFINITIONS DP
IO_UNITS OUTPUT
STATUS ERROR
DIAGONALIZATION SYMMETRIC_UPPER
ATOMS ATMCRD, ATMFIX, NATOMS, NFIXED, NFREE
DCD_IO Many of the public items in the module.
NORMAL_MODE_UTILITIES Most of the public items in the module.
POTENTIAL_ENERGY ATMDER, ATMHES, ETOTAL, GRADIENT, HESSIAN


Public Variables

None.

Public Procedures

There is a single public subroutine in this module.

SubroutinePurpose
REACTION_PATH_TRACE Generate a steepest-descent reaction path.


REACTION_PATH_TRACE

Argument Type Intent Optional Purpose
DIRECTION Character ( Len = 1 ) In No The direction in which to trace the path.
MAXSTP Integer In No The number of steps to take in tracing the path.
PRINT_FREQUENCY Integer In Yes The print frequency.
FROM_SADDLE Logical In Yes A flag to indicate the starting structure for the path tracing is a saddle point.
USE_MASS_WEIGHTING Logical In Yes The mass-weighting flag.
ENERGY_STEP Real In Yes The estimated energy decrease when taking the first step of a path away from a saddle point.
PATH_STEP Real In Yes The path-tracing step size.
SAVE_FREEQUENCY Integer In Yes The frequency for saving structures on a trajectory file.
FILE Character ( Len = * ) In Yes The trajectory file name.


Error Meaning
Unknown direction. The argument DIRECTION is neither "+" nor "-".
Path file name absent. The trajectory file name is missing.
The starting structure is not a saddle point. The starting structure does not have the correct curvature.



Stability

The algorithm used could be greatly improved. Otherwise, stable.



Back to the DYNAMO Home-Page.