[QE-users] A question regarding s8 in the dft-d3 code

[Vahid Askarpour]

Dear QE Community,

In the core.f90 of dft-d3  folder of QE-7.0, when calculating the BJ damping with version 4, the energies are given by

e6=e6+ c6/(r6+(a1*tmp+a2)**6)
e8=e8+ c8/(r8+(a1*tmp+a2)**8)

These expressions are similar to the Eqs. 5 and 6 in Journal of Computational Chemistry (https://doi.org/10.1002/jcc.21759) by Grimme et al. except that the s6 and s8 (s18 in the code) are missing. Actually s6 is set to 1.0 for version 4 but what about s8? Shouldn’t c8 change to s8*c8 in the above second equation?

Thank you,
Vahid

Vahid Askarpour
Department of physics and atmospheric science
Dalhousie University
Halifax, NS
CANADA