[Pw_forum] metallic BP?

Sun Dec 4 02:25:35 CET 2011

I'm sorry, you expressed correctly.
Can you tell us what pressure and forces you got?
What was energy difference between the two last scf steps?

      Éric.

On 12/03/2011 03:39 AM, giacsport at libero.it wrote:
>
>          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.
>
>             Éric.
>
>     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
>>
>>     _______________________________________________
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>>
>
>     -- 
>     /Be the change you wish to see in the world
>     / --- Mahatma Gandhi ---
>
>     Dr. Éric Germaneau
>     <http://www.linkedin.com/pub/%C3%A9ric-germaneau/30/931/986>
>
>     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/
>
>
>
>
>
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-- 
/Be the change you wish to see in the world
/ --- Mahatma Gandhi ---

Dr. Éric Germaneau 
<http://www.linkedin.com/pub/%C3%A9ric-germaneau/30/931/986>

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/

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