PBEsol+IVDW=20

[Fermi1976]

Hi,
I am interested in testing different functional (such as GGA=PS) and different vdW atom-pairwise (such as IVDW=20).
I use VASP 6.4.3 (single point calculations) I got an error message:
"vdw_forces_TS: ERROR unsupported xc-functional: please define parameter VDW_SR for this functional"

My question: How can I define this parameter?.

Here si my INCAR file:

Code: Select all

    PREC = Accurate
   ENCUT = 900
  IBRION = -1
     NSW = 0
    ISIF = 2
  NELMIN = 2
   EDIFF = 1.0e-08
  EDIFFG = -1.0e-07
 VOSKOWN = 1
  NBLOCK = 1
  NWRITE = 1
    NELM = 60
    ALGO = Normal (blocked Davidson)
   ISPIN = 1
  INIWAV = 1
  ISTART = 0
  ICHARG = 2
   LWAVE = .FALSE.
  LCHARG = .FALSE.
 ADDGRID = .TRUE.
  ISMEAR = 0
   SIGMA = 0.05
   LREAL = .FALSE.
 
# Van der Waals#######
  GGA = PS
IVDW = 20

Thank you
Iyad

[christopher_sheldon1]

Hi Iyad,

Thanks for your question. The Tkatchenko-Scheffler (TS) dispersion correction has only been fitted for PBE, PBE0, BLYP, B3LYP, revPBE, M06L, and M06 by TS, so it has not been parameterised for PBEsol. Instead, I would recommend using PBE+TS, where VDW_SR = 0.94 should be used, or the many-body dispersion (MBD), PBE+MBD, (MBD was specifically developed with solids in mind) with IVDW = 202.

Let me know if there's anything else that I can help you with.

Best wishes,

Chris