[Pw_forum] negative charge density!
Mousumi Upadhyay Kahaly
mousumi at jncasr.ac.in
Fri Jul 15 09:26:20 CEST 2005
Dear Sir,
Yes, i use supercell. So what should I do now?
regards, mousumi
> Hi,
>
> At this time I would like just to note that you use
> plane waves which means you use periodic boundary
> condition, i.e. a supercell.
>
> Bests,
> Eyvaz.
> --- Mousumi Upadhyay Kahaly <mousumi at jncasr.ac.in>
> wrote:
>
>> Respected Sir,
>>
>> I am trying to do calculations for a
>> molecule(Cd-2CH3COO); so
>> is there much meaning of taking more k-points
>> instead only
>> Gamma-pt?
>>
>> Secondly, I have tested pp.x and the
>> chdens.x for Cd crystal
>> system(hexagonal) with K_POINTS automatic
>> 7 7 6 -6 -6 -5
>> and
>> ecutwfc = 30.00000 Ry ,
>> ecutrho = 240.00000 Ry.
>>
>> Then also I get a negative charge of
>> -0.70243E+00 at the
>> output .xsf file & hence in xcrysden plot.
>> All these negative charges come
>> particularly on the metal
>> atom. I have done these testing for Pb crystal
>> system also
>> with both LDA and GGA pseudopotentials. For LDA
>> pseudopotential ( Pb.vdb.UPF) no negative charges
>> appear
>> whereas for GGA psp( pb_ps.uspp.UPF ) negative
>> charges appear.
>> So, what is the explanation for this negative
>> charges?
>>
>> Can you please suggest some way out to
>> get rid of this
>> problem while using GGA pseudopotential?
>>
>> Best regards,
>> mousumi
>>
>> > Hi,
>> >
>> > Did you try increase k-points instead of using
>> only
>> > Gamma-point? Besides, test also a little bit
>> larger
>> > ecutrho, say 30Ry.
>> >
>> > Bests,
>> > Eyvaz.
>> >
>> >
>> > --- Mousumi Upadhyay Kahaly <mousumi at jncasr.ac.in>
>> > wrote:
>> >
>> >> Hi all,
>> >>
>> >> This is a resubmission of my mail regarding
>> >> charge density calculation.
>> >>
>> >>
>> >
>>
> --------------------------------------------------------------------------
>> >>
>> >> Dear all,
>> >>
>> >> I am trying to do charge analysis for
>> >> Cd-di-acetate system. With
>> >> the following files for pp.x and then chdens.x,
>> as I
>> >> am plotting
>> >> the isosurfaces of charge densities with
>> XCRYSDEN, I
>> >> am getting
>> >> some negative charge;
>> >> Minimum grid value= -0.498760, and maximum
>> >> grid value= 1.09220.
>> >> How come I get such negative values(mainly around
>> >> the Cd atom, as found)
>> >> which is not negligible? What is the meaning of
>> this
>> >> NEGATIVE charge
>> >> density? Can anyone please tell me, what is the
>> >> mistake that I have made &
>> >> what should I do to get rid of this?
>> >>
>> >> Best
>> >> regards, Mousumi.
>> >>
>> >> 1. Input file for SCF pw.x run:
>> >>
>> >
>>
> =========================================================================
>> >> &CONTROL
>> >> calculation = 'scf' ,
>> >> restart_mode = 'from_scratch' ,
>> >> tstress =.true.,
>> >> outdir =
>> >>
>> '/export/mousumi/PWSCF_2.0.1/Cd_2CH3COO/ELF/tmp//' ,
>> >> pseudo_dir = '/export/mousumi/PWscf_GUI/pseudo/'
>> ,
>> >> prefix = 'Cd_di_acetate' ,
>> >> /
>> >> &SYSTEM
>> >> ibrav = 8,
>> >> celldm(1) = 50.000000,
>> >> celldm(2) = 0.30,
>> >> celldm(3) = 0.30,
>> >> nat = 15,
>> >> ntyp = 4,
>> >> ecutwfc = 25.00000 ,
>> >> ecutrho = 150.00000 ,
>> >> nosym = .false. ,
>> >> nbnd = 37,
>> >> occupations = 'smearing' ,
>> >> degauss = 0.003 ,
>> >> smearing =
>> 'methfessel-paxton' ,
>> >> nspin = 1 ,
>> >> lda_plus_u = .false. ,
>> >> /
>> >> &ELECTRONS
>> >> conv_thr = 1.0d-12 ,
>> >> mixing_beta = 0.3 ,
>> >> /
>> >> ATOMIC_SPECIES
>> >> C 12.01000 C.pbe-van_bm.UPF
>> >> H 1.00000 H.pbe-van_bm.UPF
>> >> O 15.99990 O.pbe-van_bm.UPF
>> >> Cd 112.4000 Cd.pbe-van.UPF
>> >> ATOMIC_POSITIONS {angstrom}
>> >> O -2.181887203 -0.288129610 -0.491107761
>> >> O -1.981730329 -0.473233788 1.733566845
>> >> C -2.708815067 -0.432156029 0.673205720
>> >> C -4.208743648 -0.532432174 0.801074150
>> >> H -4.477821741 -1.131831132 1.680695448
>> >> H -4.617325903 0.482417907 0.942246198
>> >> H -4.646292897 -0.952999527 -0.113856718
>> >> Cd -0.137714936 -0.219807184 0.461048531
>> >> C 2.434799121 -0.031519760 0.246012557
>> >> O 1.729314564 1.038606335 0.354394821
>> >> O 1.885568682 -1.194338232 0.239827517
>> >> C 3.936349099 0.076394885 0.148653197
>> >> H 4.228550980 1.056061785 -0.250634315
>> >> H 4.360345258 -0.025882832 1.161749300
>> >> H 4.338742013 -0.738423646 -0.467966988
>> >>
>> >> K_POINTS {automatic}
>> >> 1 1 1 0 0 0
>> >>
>> >
>>
> ==========================================================================
>> >>
>> >> 2. After the pw.x run with above file, with files
>> in
>> >> "tmp" dir, file for pp.x
>> >>
>> >
>>
> ===========================================================================
>> >> &inputpp
>> >> prefix = 'Cd_di_acetate'
>> >> outdir =
>> >>
>> '/export/mousumi/PWSCF_2.0.1/Cd_2CH3COO/ELF/tmp//'
>> >> filplot = 'Cd_2CH3COO_chden'
>> >> plot_num = 0
>> >> /
>> >>
>> >
>>
> ==========================================================================
>> >>
>> >> 3. Then, input file for chdens.x
>> >>
>> >
>>
> ==========================================================================
>> >> &input
>> >> nfile = 1
>> >> filepp(1)='Cd_2CH3COO_chden'
>> >> iflag = 3
>> >> output_format = 5
>> >> /
>> >>
>> >
>>
> ==========================================================================
>> >>
>> >>
>> >>
>> >>
>> >> _______________________________________________
>> >> Pw_forum mailing list
>> >> Pw_forum at pwscf.org
>> >>
>> http://www.democritos.it/mailman/listinfo/pw_forum
>> >>
>> >
>> >
>> >
>> >
>> > __________________________________
>> > Yahoo! Mail
>> > Stay connected, organized, and protected. Take the
>> tour:
>>
> === message truncated ===
>
>
>
>
> ____________________________________________________
> Start your day with Yahoo! - make it your home page
> http://www.yahoo.com/r/hs
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
More information about the users
mailing list