[Wien] how to use optB88-vdW with wien2k-18.1

[tran at theochem.tuwien.ac.at]

Hi,

The file case.r2v_nlvdw will be generated and used during the
calculation. You don't need to care about it.

The steps for DOS, band structure and optics are exactly the same
as with usual LDA or GGA.

The extra computational time due to NLVDW does not depend on
RKMAX or k-mesh. It depends on the size of the unit cell and on
the value of plane-wave expansion cutoff GMAX in case.innlvdw.

If you don't need to optimize position of atoms in the
unit cell (i.e., no "-min"), then replace "T" by "F" in the
last line of case.innlvdw. This will reduce significantly
the NLVDW computational time.

F. Tran

>Dear Wien2k users
>
>I have a few questions for optB88-vdW with Wien2k_18.1.
>
>
>I need to use optB88-vdW for a perovskite structure.
>
>What I found from the mailing list and UG;
>
>1. Need two files case.in0 and case.innlvdw to use this function and can optimize the structure with this NL functional.
>2. One should add "–nlvdw" run(sp)_lapw script.
>
>
>Now I have below queries:
>
>1. It is mentioned to use "case.r2v_nlvdw" file [1], but in UG nothing is said about this file. If we need to use
>case.r2v_nlvdw then how to recall it?
>
>2. Do we need to treat the step in the same way as we do for doss, optical and band structure or we need to modify them? If
>we need to modify these steps then what are the necessary changes (x -h xxxx show nothing about -nlvdw for calculating these
>properties)?
>
>3. How expensive is in comparison to PBE? If I use 12x12x12 mesh for PBE then how much I can reduce the mesh size (running on
>16 processor CPU)?
>
>
>[1] https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16549.html
>
>
>
>Thanks and regards
>
>K.C. Bhamu