The correct DFT label for rVV10 is "rVV10", not "vv10". By
setting "vv10", all you get is the nonlocal part, with no
other XC contributions. The output is misleading:
Exchange-correlation = VV10 ( 0 0 0 0 3)
but the four 0's mean respectively "no exchange", "no correlation",
"no gradient correction to exchange", "no grad. corr. to correlation".
In the svn version there is a further check to prevent this kind of
misunderstanding, but it was added only recently.
Paolo
On Thu, 2014-10-16 at 12:03 +0100, Andrea Floris wrote:
> Dear quantum-ESPRESSO users,
>
>
> I am running some calculations with espresso 5.1 and the van der
> Waals
> rVV10 functional.
>
>
> First, with the program:
>
>
> generate_rVV10_kernel_table.x
>
>
>
>
> I generated the universal file:
>
>
> rVV10_kernel_table
>
>
>
>
>
>
>
> Then I tried three systems up to now,
>
> 1. two water molecules (insulating)
> 2. a surface with some organic molecules on top (insulating). This is
> the system I am actually interested in.
> 3. graphite, with some smearing
>
>
> In the first two cases
> the energy seems to reach convergence but then
> suddenly the scf accuracy increases , like this
>
>
> estimated scf accuracy < 0.06260677 Ry
> estimated scf accuracy < 0.04294545 Ry
> estimated scf accuracy < 0.02031181 Ry
> estimated scf accuracy < 0.01888999 Ry
> estimated scf accuracy < 0.01019674 Ry
> estimated scf accuracy < 0.00222739 Ry
> estimated scf accuracy < 0.00317661 Ry
> estimated scf accuracy < 0.00370097 Ry
> estimated scf accuracy < 0.00396386 Ry
> estimated scf accuracy < 0.00018021 Ry
> estimated scf accuracy < 1.54950129 Ry
> estimated scf accuracy < 1.54973018 Ry
> estimated scf accuracy < 1.54679045 Ry
>
>
>
> ...and so on and does not converge after 100 steps. I tried to reduce
> the mixing to 0.1, or even smaller, without any effect. (see
> attachments)
>
>
> For the more complex surface+molecules system, the behaviour is
> similar.
>
>
> For the graphite with some smearing, the eigenvectors of the
> Hamiltonian fail to converge in the diagonalization process. (see
> attachment)
>
>
> I would appreciate some help to ascertain if:
>
>
>
> 1. I am doing something wrong somewhere?
> 2. there is an issue in the convergence of rVV10 with insulators?
> 3. is there a (different) issue with rVV10 and smearing?
>
>
> I am aware that water calculations with rVV10 have been successfully
> performed, so I would appreciate very much your suggestions.
>
>
> Thanks
>
>
> Best,
> Andrea
>
>
> --
> Dr Andrea Floris
> Research Associate
> King's College London
> Strand, London WC2R 2LS
> United Kingdom
> Phone: +44 (0) 207 848 2064
> Fax : +44 (0) 207 848 2420
> Location: Strand Building, 4th floor, Room 4.02
> Emails: [email protected], [email protected]
>
> _______________________________________________
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> http://pwscf.org/mailman/listinfo/pw_forum
>
>
--
Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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