Hi Eric, sorry. I expressed my point maybe in a misleading way...I mean, i found a gap metallic (Homo is highest in energy than Lumo) but the system is reported to be a wide bandgap semiconductor (Gap > 2. eV)"highest occupied, lowest unoccupied level (ev): 6.1092 5.4104"HOMO=6.109 LUMO=5.4104 (as far as I understand)....the gap is 0.7 eV only if you switch HOMO and LUMO The structure is the experimental one I found from a previous paper and it was optimized with Gaussian PBC
Thanks,G ----Messaggio originale---- Da: germaneau at gucas.ac.cn Data: 03/12/2011 16.32 A: "giacsport at libero.it"<giacsport at libero.it>, "PWSCF Forum"<pw_forum at pwscf.org> Ogg: Re: [Pw_forum] metallic BP? Hey Giacomo, Forgive my ignorance but why do you say that the "scf" calculation is a system that "should be" metallic ? To me it has a band gap of .7 ev. What do you mean by wide band gap semiconductor ? What band gap value do you expect to get? May be the wide band gap behavior you mention does not occur at 0K. I guess you double checked whether your system is fully relaxed. ?ric. On 12/02/2011 09:20 PM, giacsport at libero.it wrote: Dear All, I am doing calculations on a 2 atom primitive cell of Boron Phosphide. What I obtain from the "scf" calculation is a system that "should be" metallic.... Indeed "highest occupied, lowest unoccupied level (ev): 6.1092 5.4104" -->( As far as I understand, Homo lies 0.7 eV above the LUMO) but of course this system is a wide-gap semiconductor. I am not able to figure out the reason for such behaviour. I have tested the same system (rhombohedral cell, a=b=c=6.06 Bohr, alpha=beta=gamma=60deg) in several machines finding always the same result. I attach the input file and the header of the two pseudos (USPP/GGA) I am using. Thanks in advance for any comments. My best, Giacomo &control calculation = 'scf' restart_mode='from_scratch', prefix='BP', tprnfor = .true., tstress = .true., wf_collect=.true., pseudo_dir='/home/giacomo/GGA/', outdir='/home/giacomo/GGA/' / &system ibrav= 4, celldm(1) =6.061296108, celldm(3)=1, nat= 2, ntyp= 2, ecutwfc =50., nbnd = 50, / &electrons diagonalization='david' mixing_mode = 'plain' mixing_beta = 0.7 conv_thr = 1.0d-8 / ATOMIC_SPECIES B 10.811 B.UPF P 30.974 P.UPF ATOMIC_POSITIONS (crystal) B 0.0 0.0 0.0 P 0.25000 0.25000 0.250000 K_POINTS (automatic) 6 6 6 0 0 0 For BORON: <PP_INFO> Generated using Vanderbilt code, version 7 3 5 Author: unknown Generation date: 20 6 2004 Automatically converted from original format 0 The Pseudo was generated with a Non-Relativistic Calculation 1.00000000000E+00 Local Potential cutoff radius nl pn l occ Rcut Rcut US E pseu 2S 2 0 2.00 10.00000000000 1.50000000000 -0.69693392995 2P 2 1 1.00 10.00000000000 1.53000000000 -0.26855658626 </PP_INFO> <PP_HEADER> 0 Version Number B Element US Ultrasoft pseudopotential T Nonlinear Core Correction SLA PW GGX GGC PW91 Exchange-Correlation functional 3.00000000000 Z valence -5.70038942945 Total energy 0.0000000 0.0000000 Suggested cutoff for wfc and rho 1 Max angular momentum component 781 Number of points in mesh 2 4 Number of Wavefunctions, Number of Projectors Wavefunctions nl l occ 2S 0 2.00 2P 1 1.00 </PP_HEADER> --------------------------------- For PHOSPHORUS <PP_INFO> Generated using Vanderbilt code, version 7 3 5 Author: unknown Generation date: 20 6 2004 Automatically converted from original format 1 The Pseudo was generated with a Scalar-Relativistic Calculation 1.60000000000E+00 Local Potential cutoff radius nl pn l occ Rcut Rcut US E pseu 3S 3 0 2.00 10.00000000000 1.70000000000 -1.03015496458 3P 3 1 3.00 10.00000000000 1.70000000000 -0.40774343239 </PP_INFO> <PP_HEADER> 0 Version Number P Element US Ultrasoft pseudopotential T Nonlinear Core Correction SLA PW GGX GGC PW91 Exchange-Correlation functional 5.00000000000 Z valence -17.57767183737 Total energy 0.0000000 0.0000000 Suggested cutoff for wfc and rho 2 Max angular momentum component 903 Number of points in mesh 2 5 Number of Wavefunctions, Number of Projectors Wavefunctions nl l occ 3S 0 2.00 3P 1 3.00 </PP_HEADER> ------------------------------------------ Giacomo Giorgi Department of Chemical System Engineering, School of Engineering, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan _______________________________________________ Pw_forum mailing list Pw_forum at pwscf.org http://www.democritos.it/mailman/listinfo/pw_forum -- Be the change you wish to see in the world ? Mahatma Gandhi ? Dr. ?ric Germaneau Graduate University of Chinese Academy of Sciences College of Physical Sciences Yuquan Road 19A Beijing 100049 China Please, if possible, don't send me MS Word or PowerPoint attachments Why? See: http://www.gnu.org/philosophy/no-word-attachments.html -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20111203/efd48493/attachment.htm