[Pw_forum] Negative charge !

[Axel Kohlmeyer]

On Mon, 26 Feb 2007, Von Braun Nascimento wrote:

VN> Dear all,  
VN> 
VN> I am trying to generate some charge plots for a prototype bulk La/Sr
VN> manganite. 
VN> The 1-D charge plot along Sr-O atoms is negative close to the Sr core,
VN> although it does not happen along La-O atoms. I've checked PW forum archives
VN> and there is a comment about increasing the number of k points or the
VN> cut-off energy.  I've increased both (see attached input files) and nothing
VN> has changed so far. Why do this negative charge problem is present only
VN> close to Sr ? 

hmmm, you don't say how negative. 
perhaps it is due to the pseudopotential?

[akohlmey at zero 038-Sr-gpw-nsp-campos]$ grep nega Sr_ps.out 
     most negative density at mesh point  498 at   0.29698 au with value  -0.00135
     most negative density at mesh point  499 at   0.30206 au with value  -0.00116
     most negative density at mesh point  481 at   0.22262 au with value  -0.00101
     most negative density at mesh point  495 at   0.28226 au with value  -0.00384

axel.

VN> Thanks in advance. 
VN> 
VN> Regards, Von  
VN> 
VN> 
VN> 
VN> ============================================================================
VN> =========
VN> PWSCF input file :
VN> 
VN>  &control
VN>     calculation='scf'
VN>     restart_mode='from_scratch',
VN>     pseudo_dir = '/home/von/Mang-DFT/BULK/',
VN>     outdir='/home/von/Mang-DFT/BULK/tmp/'
VN>     prefix='Mang-scf'
VN>     tstress = .true.
VN>     tprnfor = .true.
VN>  /
VN>  &system
VN>     ibrav = 6, celldm(1) =  7.323629, celldm(3)= 5.199886,nat= 24, ntyp= 4,
VN>     ecutwfc =  30.0, ecutrho = 300.0
VN>     occupations='smearing', smearing='methfessel-paxton', degauss=0.02  /
VN> &electrons
VN>     diagonalization='david'
VN>     conv_thr = 1.0e-8
VN>     mixing_beta = 0.7
VN>  /
VN> ATOMIC_SPECIES
VN>  O    15.9994     O.pbe-van_ak.UPF
VN> Mn    54.938045   Mn.pbe-sp-van.UPF
VN> La   138.90547    La.pbe-nsp-van.UPF
VN> Sr    87.62       Sr.pbe-nsp-van.UPF
VN> ATOMIC_POSITIONS
VN> O      0.50000  0.50000   0.00000
VN> La     0.00000  0.00000   0.06947
VN> Mn     0.50000  0.50000   0.51723
VN> O      0.50000  0.00000   0.52373
VN> O      0.00000  0.50000   0.52373
VN> O      0.50000  0.50000   1.01850
VN> La     0.00000  0.00000   1.01850
VN> Mn     0.50000  0.50000   1.51977
VN> O      0.50000  0.00000   1.51327
VN> O      0.00000  0.50000   1.51327
VN> O      0.50000  0.50000   2.03700
VN> La     0.00000  0.00000   1.96753
VN> O      0.00000  0.00000   2.59994
VN> Sr     0.50000  0.50000   2.66941
VN> Mn     0.00000  0.00000   3.11718
VN> O      0.50000  0.00000   3.12368
VN> O      0.00000  0.50000   3.12368
VN> O      0.00000  0.00000   3.61844
VN> Sr     0.50000  0.50000   3.61844
VN> Mn     0.00000  0.00000   4.11971
VN> O      0.50000  0.00000   4.11321
VN> O      0.00000  0.50000   4.11321
VN> O      0.00000  0.00000   4.63695
VN> Sr     0.50000  0.50000   4.56748
VN> K_POINTS (automatic)
VN>  13 13 13 0 0 0
VN> 
VN> ===========================================================================
VN> PP input file :
VN> 
VN>  &inputpp
VN>     prefix  = 'Mang-scf'
VN>     outdir = '/home/von/Mang-DFT/BULK/tmp/'
VN>     filplot = 'Mangcharge'
VN>     plot_num= 0
VN>  /
VN>  &plot
VN>     nfile = 1
VN>     filepp(1) = 'Mangcharge'
VN>     weight(1) = 1.0
VN>     iflag = 1
VN>     output_format = 0
VN>     fileout = 'Sr-Oplane.dat'
VN>     e1(1) =  0.00000, e1(2) =-0.50000, e1(3) = -0.45426,
VN>     x0(1) = 0.50000, x0(2)= 0.50000, x0(3) = 4.56748,
VN>     nx=   100
VN>  /
VN> 
VN> ============================================
VN> 
VN>          Dr. Von Braun Nascimento
VN> 
VN>         Pos-doc Research Associate
VN> 
VN>        Dept of Physics and Astronomy
VN>          University of Tennessee
VN>                     & 
VN>   Materials Science and Technology Division
VN>        Oak Ridge National Laboratory 
VN> 
VN> ============================================ 
VN> 
VN> _______________________________________________
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VN> Pw_forum at pwscf.org
VN> http://www.democritos.it/mailman/listinfo/pw_forum
VN> 

-- 
=======================================================================
Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
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Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
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