a Stewart Computational Chemistry, 15210 Paddington Circle, Colorado Springs, CO 80921, USA
*Corresponding author: MrMOPAC@att.net
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Documentation for PARAM
Overview of PARAM detailing keywords, usage
strategies, etc.
PARAM.zip contains all the material for parameter optimization and surveys to determine accuracy to be done. The main components are:
A utility "files" that constructs a list of the reference data files in the order of the periodic table. Thus the file for [H]+ is first and Bi2I6 is last.
A utility "select" that generates a sub-set of the reference file list created by "files." Criteria for the subset can be either the list of elements or the set of elements available within each method.
A utility "Set_up_Map" that constructs a HTML list of all reference data being used and a link to a hypertext graphical representation of each datum. This graphical representation requires that Jsmol and Firefox are installed.
A program "Stats" that constructs HTML tables of reference heats of formation, dipole moments, ionization potentials, and geometric reference data, and the errors in each method for each datum. A second set of tables lists the same quantities but for each element, instead of each datum.
The program MOPAC. To avoid confusion, the particular version of MOPAC that was used in method development is included.
The program PARAM, together with several data-sets illustrating parameter optimization and surveys of results.
Recommended procedure for setting up a starting environment
All method development work should be done on a Windows 10 or 11 operating system.
Create a folder with an appropriate name, for example PARAM . This will be used to contain all the material used in optimizing parameter values.
Unzip the contents of the ZIP file into the folder..
Review the command files. Each command file illustrates a specific action.
Run the command file "Construct all.cmd" This will set up a complete working environment for method development.Time required: ~15 hours.
Before proceeding further, carefully examine the new files and verify that the contents make sense.
Parameter optimization
A single command, "Method-development - Improve PM6-ORG.cmd", will run the parameter optimization process. The example given uses 3306 reference data, and optimizes 318 parameters. Once started, it would run for many days, even weeks. Once started, the rate of convergence of the parameters can be monitored, and when appropriate, the job should be killed. As soon as the job is understood, this command should be modified to use the current project.
Caveats
The main collection of reference data, ,i.e., the set "Data Normal", has not been curated, and should be regarded as being of limited reliability. Warnings such as "Deadly error detected ..." and "ALL CONVERGERS ..." when all of "Data Normal" is used can be ignored.
Conversely, the reference data files in the data-sets used in method development, i.e., those mentioned in PM6-ORG.dat such as "core.txt", have been curated. This was a necessary step in order to ensure that the values of the parameters could be optimized correctly. Errors that were ignored when all of "Data Normal" was used should not be ignored when method development is being done.
In method development, individual data that take a long time, 100 or more seconds, to calculate should be deleted unless they are deemed necessary for the new method.