Hi Paolo, thanks for the reply and escuse me for the previous lacking description of the problem. I have a question that you for sure will be able to reply.
It seems that I was able to fix the problem. I will try to explain. In my first attempt I was using the Primitive Cell of BP consisting of two atoms. It is a rhombohedral cell, a=b=c=6.06 Bohr and alpha=beta=gamma=60 deg (ibrav= 4, celldm(1) =6.06, celldm(3)=1) B 0.0000 0.0000 0.0000 P 1.1373 1.1373 1.1373 -2 0.0000 2.2745 2.2745 -2 2.2745 0.0000 2.2745 -2 2.2745 2.2745 0.0000 (first 2 lines atomic coordinates, last three the lattice vectors) reported in the Supplementary Materials of THE JOURNAL OF CHEMICAL PHYSICS 123, 174101 (2005) It gave as result that strange bandgap I reported before (formally no gap). espresso.4.1.3 (both serial and parallel) Then I used exactly the same atomic position and configuration (2 atoms, 1 B and 1 P) but with the lattice parameters of the Conventional Cell (ibrav= 2, celldm(1) =8.575576536) and in this case I found perfect agreement (of course with some obvious DFT underestimation of the gap). Thus, as far as I understand, if I have the Primitive Cell coordinates I have to use in any case the Conventional Cell lattice vectors. Is it correct? Thanks in advance and excuse me once more! My very best, Giacomo ---------------------------------- Giacomo GIORGI Department of Chemical System Engineering, School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Ja >----Messaggio originale---- >Da: giannozz at democritos.it >Data: 03/12/2011 11.04 >A: <giacsport at libero.it>, "PWSCF Forum"<pw_forum at pwscf.org> >Ogg: Re: [Pw_forum] metallic BP? > > >On Dec 3, 2011, at 9:39 , giacsport at libero.it wrote: > >> The structure is the experimental one I found from a previous paper >> and it was optimized with Gaussian PBC > >are you sure? it yields very high forces and a very large stress. >It also has just 2 symmetries. > >Reminder to everybody reporting problems: >- if you use pseudopotentials from www.quantum-espresso.org, > please do not change the names of pseudopotential files >- please always report the version of QE you are using > >P. >--- >Paolo Giannozzi, Dept of Chemistry&Physics&Environment, >Univ. Udine, via delle Scienze 208, 33100 Udine, Italy >Phone +39-0432-558216, fax +39-0432-558222 > > > > >