http://sobereva.com/wfnbbs/viewtopic.php?id=845 Tue, 04 Jul 2023 11:56:55 +0000 FluxBB http://sobereva.com/wfnbbs/viewtopic.php?pid=3238#p3238 Dear all,
I recently tried to use Multiwfn to compute C6 parameters based on Tkatchneko-Scheffer method. Nevertheless, for the same dataset, the values I get are found to be by a factor of two less accurate than what they reported in their original paper.
The reason seems to be due to the computation of free atom volumes either via G16 or the default free atom spherical average densities hard-coded in Multiwfn (the same issue also has been discussed for Q-Chem code https://manual.q-chem.com/5.4/sect_TS.html)
For that, I would be so thankful for some hints for good practice in computations leading to more accurate estimation of free-atom volumes for open-shell atoms, specifically about using symmetry or not, computing based on restricted open-shell or unrestricted, and setting initial guesses.
Thank you in advance and best regards,
Amin

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