Introduction to MOPAC
What is it used for?
In practice MOPAC is used:
- to optimize a structure
- -variables to be optimized are followed by the "1" flag in the input file.
- to obtain a description of the molecular orbitals, coefficients, charges.
- -the keywords VECTORS and LOCALIZE will print the coefficients in the output file.
- to perform a line search, describing how the energy (heat of formation) depends on one
variable (distance, angle, torsion)
- -the variable to be scanned is marked by a "-1" flag.
- -values are added at the bottom of the input file.
- -MOLDEN can visualize the output of a line search (plot and structures)
- to do a grid search, varying two variables
- -the number of points and the step size are specified in the keyword line.
- -the data from a grid search can be
plotted by e.g. Gnuplot.
- to search for transition states in reactions
- -e.g. optimize the maximum resulting from a line search, or the saddle
point in a grid surface.
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Last updated on August 22nd, 1996