Dear all
I don't want to raise the confusion level, so please correct me if I'm
wrong... If you want to calculate a heavily approximate absorption
spectrum of a (large and non-symmetrical) periodic system after a
ground state hybrid calculation, there used to be an option in the
turbo_davidson.x and turbo_lanczos.x codes, namely no_hxc=.true.,
which permits an independent-electron calculation. At least, hybrid
functionals and Gamma ground states should be properly treated by such
codes, resulting in an absorption spectrum compatible with those
obtained by using epsilon.x, which, AFAIK, calculates
<occupied|r|virtual> contributions to the absorption spectrum.
However, I don't know how much this kind of calculation is expensive
for large supercells. Of course if you are not interested in
absorption, then my suggestion is nonsense...
HTH
Giuseppe
Quoting Lorenzo Paulatto <[email protected]>:
Also, epsilon.x cannot use symmetry-reduced grids, which would be a
huge wast of time with hybrids, but you can use open_grid.x after
the pw.x calculation too obtain the full grid and work around this
problem.
cheers
On 4/8/20 6:38 PM, Paolo Giannozzi wrote:
I think epsilon.x assumes that the dipole element of x can be
computed using [H,x]=p\hbar/m. The exchange potential is nonlocal,
so its commutator with x will yield an additional term that is not
accounted for. Not sure how important it is in practice. Do I
remember correctly that epsilon.x also does not take into account
the nonlocal pseudopotential contribution?
Paolo
On Wed, Apr 8, 2020 at 4:29 PM Manu Hegde <[email protected]
<mailto:[email protected]>> wrote:
Hi Michal,
Yes, it is possible.I did use both supercell and hybrid
calculations. It did work.
Manu
On Wed, Apr 8, 2020 at 10:08 AM Michal Krompiec
<[email protected] <mailto:[email protected]>> wrote:
Hello,
Is it possible to use epsilon.x on results of a calculation with a
hybrid functional (supercell, gamma point only)?
Thanks,
Michal Krompiec
Merck KGaA
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Phone +39-0432-558216, fax +39-0432-558222
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GIUSEPPE MATTIOLI
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