search

patonlab / GoodVibes

Calculate quasi-harmonic free energies from Gaussian output files with temperature and other corrections
http://www.patonlab.colostate.edu
MIT License
129 stars 50 forks source link

Symmetry correction of homonuclear diatomic molecules #50

Closed RaphaelRobidas closed 2 years ago

RaphaelRobidas commented 2 years ago

I was looking at the symmetry correction of homonuclear diatomic molecules, and I am wondering if the rotational entropy correction is being applied twice with --ssymm.

In order to calculate the rotational entropy, Goodvibes parses the rotational symmetry number from the Gaussian output file. This seems to always be 1, except for homonuclear diatomic molecules, where it is 2. Goodvibes thus calculates the rotational entropy with this symmetry number. The free energy calculated by Goodvibes is exactly the same as the one in the Gaussian output file.

With the --ssymm keyword, Goodvibes applies an additional correction of RTln(2) to the free energy. Is that actually correct or is Goodvibes applying a duplicate symmetry correction?

jvalegre commented 2 years ago

Thanks we fixed this issue - please, let us know if the problem persists.