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Introducing OPLSAA version 2023
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@jewettaij jewettaij released this 03 Dec 08:36
· 26 commits to master since this release
v2.21.1
1c57100
  • OPLSAA has been upgraded to the 2023 version with numerous changes.
  • The OPLSAA examples (and the "loplsaa.lt" file used by LOPLS) have been updated as well.

Many thanks to Domenico Marson who wrote the program that converts BOSS files into moltemplate format!

To use the new "oplsaa.lt" file, you must change the @atom numbers in your .lt files

Many new atom types have introduced into OPLSAA since the previous (moltemplate) version (from 2008). The same atom types are present in the new version, but the @atom numbers assigned to them have changed (to make room for these new atom types). So you must update the @atom type numbers in your .lt files that use "oplsaa.lt".

Alternatively, you can continue using the old version of "oplsaa.lt" and "loplsaa.lt"

...without changing your @atom type numbers. But the .lt file names have changed. You must replace "import oplsaa.lt" with "import oplsaa2008.lt" everywhere it appears in your .lt files. (If you are using LOPLS, then also replace "import loplsaa.lt" with "import loplsaa2008.lt") To see how this is done, see the old examples.

WARNING: The new (2023 version) of OPLSAA is highly experimental.

Please understand the risks of using this new force field.

And please report any problems that you find with this new version.

Specific concerns with the 2023 vrsion:

  • The improper interactions have not been tested carefully.
  • The new version of OPLSAA gives you many additional choices for your dihedral, angle, and bond interactions. This makes it possible for you to improve your simulation accuracy, but it also requires more effort on your part. To see the list of choices, you must now run moltemplate with the "-report-duplicates bytype __" arguments. For example:
moltemplate.sh  system.lt  -report-duplicates bytype __
  • If you see a file named "warning_duplicate_dihedrals.txt", "warning_duplicate_angles.txt", "warning_duplicate_bonds.txt", or "warning_duplicate_impropers.txt" after running moltemplate, then it is a good idea to read the first few warning messages
    in those files and modify your .lt files accordingly (for example, by adding a custom "Data Dihedrals" section). Several examples demonstrate how to do that, including butane.lt and benzoic_acid.lt

Remaining work to do:

  • The list of improper interactions generated by the "oplsaa2lt.py" script is incorrect. (I'll worry about this later.) But this should not be an issue for users who just want to use the existing "oplsaa.lt" file included with this release. (That file was corrected by hand.)

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