[Pw_forum] SCAN + rVV10

[Paolo Giannozzi]

I suspect that if you specify 'scan' (or any other meta-GGA), the code
follows a different execution path with respect to all other cases, in
which only 'scan' is used. So it is likely that right now you cannot use
'scan' together with anything else

Paolo

On Mon, Sep 25, 2017 at 1:50 PM, Claudio Antonio Perottoni <caperott at ucs.br>
wrote:

> Hi,
>
> I am giving a try to SCAN+rVV10 using the master branch of QE available at
> https://github.com/QEF/q-e as of Sept. 24, 2017 (PWSCF v.6.2MaX). QE was
> compiled against libxc (trunk version > 3.0.0) and rVV10 kernel table was
> generated by *generate_rVV10_kernel_table.x* and copied to the pseudo
> dir. As a test case, I chose hexagonal boron nitride.
>
> The issue I am facing with is that pw.x returns the same energies for
> input_dft = 'scan' and for input_dft = "scan+sla+pw+rw86+pbc+vv10" (i.e.,
> for SCAN + rVV10). The code seems to identify correctly the string given to
> input_dft (e.g., for input_dft = 'scan' the output file gives
> "Exchange-correlation = SCAN ( 0 0 0 0 0 5)" and, for input_dft =
> "scan+sla+pw+rw86+pbc+vv10", the output files gives "Exchange-correlation =
> SCAN+SLA+PW+RW86+PBC+VV10 ( 1 4 13 4 3 5)"). In both cases, however, I got
> exactly the same energy after SCF convergence.
>
> Using the same input file with just rVV10 worked like a charm, giving a
> good estimate for the hexagonal boron nitride interplanar distance.
> Furthermore, when running pw.x with input_dft = 'rVV10' (or, for that
> matter, "sla+pw+rw86+pbc+vv10") I got the following in the output file:
>
> Carrying out rVV10 run using the following parameters:
> Nqs = 20 Nr_points = 1024 r_max = 100.000
> b_value = 6.30000 beta = 0.00901
> q_mesh = 0.00010000 0.00030000 0.00058939 0.00100810
> 0.00161396 0.00249058 0.00375900 0.00559430
> 0.00824984 0.01209221 0.01765183 0.02569619
> 0.03733578 0.05417739 0.07854596 0.11380545
> 0.16482331 0.23864234 0.34545298 0.50000000
>
> The above message does not appears in the output file when using input_dft
> = "scan+sla+pw+rw86+pbc+vv10".
>
>
> Here is the input file I am using in these tests:
>
> &CONTROL
> title = 'hBN'
> calculation = 'scf'
> restart_mode = 'from_scratch'
> outdir = './files'
> wfcdir = './files'
> pseudo_dir = "../pseudo"
> prefix = 'hbn'
> disk_io = 'default'
> verbosity = 'default'
> nstep = 400
> /
>
> &SYSTEM
> space_group = 194
> a = 2.503374
> c = 6.80
> origin_choice = 1
> nat = 2
> ntyp = 2
> ecutwfc = 120
> ecutrho = 480
> input_dft = "scan+sla+pw+rw86+pbc+vv10"
> /
>
> &ELECTRONS
> electron_maxstep = 200
> conv_thr = 1.0D-9
> diago_thr_init = 1e-4
> startingpot = 'atomic'
> startingwfc = 'atomic'
> mixing_mode = 'plain'
> mixing_beta = 0.5
> mixing_ndim = 8
> diagonalization = 'david'
> /
>
> ATOMIC_SPECIES
> B 10.8110000000 B.pbe-hgh.UPF
> N 14.0067000000 N.pbe-hgh.UPF
>
> ATOMIC_POSITIONS crystal_sg
> B 0.33333333333333 0.66666666666667 0.25000000000000
> N 0.33333333333333 0.66666666666667 0.75000000000000
>
> K_POINTS automatic
> 21 21 7 0 0 0
>
> It seems that rVV10 is not being used at all in calculations with
> input_dft = "scan+sla+pw+rw86+pbc+vv10". Maybe this is an invalid
> combination of keywords?
>
> Regards,
> Claudio
>
> --
> *********************************************************************
> Claudio A. Perottoni
>
> Universidade de Caxias do Sul
> Rua Francisco Getúlio Vargas, 1130
> 95070-560 Caxias do Sul - RS - Brazil
> *********************************************************************
>
>
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-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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