TDHF: unexpected output parameters in OUTCAR
Posted: Thu Mar 09, 2017 10:13 pm
I am running the TDHF example for Silicon using the INCAR from https://cms.mpi.univie.ac.at/wiki/index ... lculations and the usual POSCAR, POTCAR, and KPOINTS from http://www.vasp.at/vasp-workshop/examples/Si_BSE.tgz.
While my calculations seem to produce reasonable results, there is something a bit unexpected in the OUTCAR. Specifically, I use:
ALGO = TDHF; LHFCALC = .TRUE. ; HFSCREEN = 0.2; AEXX=0.25
in the INCAR. The OUTCAR says "parameters for screened Coulomb W: AEXX= 0.2500000 HFSCREEN= 0.2000000" as expected. Rather unexpectedly though, it also says:
Exchange correlation treatment:
GGA = -- GGA type
...
LHFCALC = T Hartree Fock is set to
...
AEXX = 1.0000 exact exchange contribution
HFSCREEN= 0.0000 screening length (either q_TF or 0.3 A-1)
HFSCREENC= 0.2000 screening length for correlation (either q_TF or 0.3 A-1)
...
Why is AEXX = 1.0 and HFSCREEN = 0.0 in the exchange-correlation block in conflict with the INCAR and the "parameters for screened Coulomb" written out later on?
While my calculations seem to produce reasonable results, there is something a bit unexpected in the OUTCAR. Specifically, I use:
ALGO = TDHF; LHFCALC = .TRUE. ; HFSCREEN = 0.2; AEXX=0.25
in the INCAR. The OUTCAR says "parameters for screened Coulomb W: AEXX= 0.2500000 HFSCREEN= 0.2000000" as expected. Rather unexpectedly though, it also says:
Exchange correlation treatment:
GGA = -- GGA type
...
LHFCALC = T Hartree Fock is set to
...
AEXX = 1.0000 exact exchange contribution
HFSCREEN= 0.0000 screening length (either q_TF or 0.3 A-1)
HFSCREENC= 0.2000 screening length for correlation (either q_TF or 0.3 A-1)
...
Why is AEXX = 1.0 and HFSCREEN = 0.0 in the exchange-correlation block in conflict with the INCAR and the "parameters for screened Coulomb" written out later on?