| 9:22:15 AM PDT - Wed, Aug 28th 2019 |
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There has been quite some buzz about results from the Wheeler computational chemistry group, showing that popular grids used for DFT integration can give different free energies for a molecule depending on its orientation relative to the cartesian axes. In particular, the relative free energy of isomers can vary greatly simply by calculating different orientations! The authors show that if a very large grid is used, the rotational dependence of DFT can be eliminated, but using larger grids of course takes more computational resources.
https://chemrxiv.org/articles/Popular_Integration_Grids_Can_Result_in_Large_Errors_in_DFT-...
The authors recommend that researchers study their molecules in a variety of orientations using a moderate grid, and see if energy differences are vast. If so, then use of a larger grid could be necessary.
My question is, does NWChem (or other free programs) offer a convenient way to do a global rigid rotation of an input molecule? I'd like to generate several different orientations to see if NWChem's (fine) grid is sufficient for my purposes.
Thank you!
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