Dear Cristian As usual, what is not suggested should be tested...:-) AFAIK you should do not too much harm if you use a PBE pseudopotential in a input_dft='vdwdf' calculation. If you are able to generate a rPBE pseudopotential, you may like to check differences on the same systems used in the related papers (graphite, ...). Yours G.
On Monday 08 April 2013 15:55:42 Cristian Degli Esposti Boschi wrote: > >> Or a GGA (say C.pbe-mt_fhi.UPF in my case) > > > > All the vdW corrections (semiempirical DFTD2 included, london=.true., > > in &system) are well tested with a given kind of xc functional. This > > is often discussed in the related papers. If you are not certain of > > > the functional recipes, look into the funct.f90 file. But this is not > > a hard limit. You may build your own functional, including vdW. I've > > tested, with PBE pseudopotentials, an hybrid+vdW functional time ago > > ('sla+pw+hse+vdw1'), with good results on molecule-surface > > interactions. > > Thanks for the answers; now my question can be more specific: > suppose I want to use a pseudopotential built constructed for PBE > (say C.pbe-mt_fhi.UPF in my case). If I set input_dft = "vdw-df", > that means "sla+pw+rpb+vdw1", > as far as I can see the gradient > correction on exchange is revPBE and not PBE (third index is 4), and > also there is no gradient correction on correlation (fourth index is 0). > Is this compatible with a PBE pseudopotential file that, if used without > vdw-df specification, would report an exchange-correlation scheme > "sla+pw+pbx+pbc" (1 4 3 4 0)? > > Or, should I set something like "sla+pw+pbx+pbc+vdw1" in order > to be consistent with the PBE pseudopotential file? > > The same question may hold for Cooper's variant (c09x instead of rpb above) > > The question is on how the code works internally; at the beginning > of the output there is a warning "Any further DFT definition will be > discarded", and I wonder what it means exactly... > > Thanks again for your time. Cristian ******************************************************** - Article premier - Les hommes naissent et demeurent libres et ?gaux en droits. Les distinctions sociales ne peuvent ?tre fond?es que sur l'utilit? commune - Article 2 - Le but de toute association politique est la conservation des droits naturels et imprescriptibles de l'homme. Ces droits sont la libert?, la propri?t?, la s?ret? et la r?sistance ? l'oppression. ******************************************************** Giuseppe Mattioli CNR - ISTITUTO DI STRUTTURA DELLA MATERIA v. Salaria Km 29,300 - C.P. 10 I 00015 - Monterotondo Stazione (RM) Tel + 39 06 90672836 - Fax +39 06 90672316 E-mail: <giuseppe.mattioli at ism.cnr.it> ResearcherID: F-6308-2012