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[Josef Zwanziger <jzwanzig@dal.ca>]

Dear Mauro Sgroi,

I have never had much success on calculations with Pb when I did not include 
the 10 5d electrons as "semi-core". They are only slightly lower in energy 
than the 6s and 6p's. You might try generating a pseudopotential including 
them and see how you do. The drawback of course is that then Pb has 14 
electrons to treat instead of 4, but you can't fight the fact that the 5d's 
really are very close in energy to the 6's. 

Good luck,

Joe

On Wednesday 02 April 2008 13:04, maurosgroi@yahoo.it wrote:
> Dear Abinit users,
>
> I'm trying to generate TM pseudopotentials including spin-orbit interaction
> for Pb using the Martins2abinit code downloaded from the web site.
>
> The input file for the atom code is:
>
> pg    Lead   PRB 54 2937 (1996)
>       tm2
>  n=Pb c=pwr
>        0.0     0.0       0.0       0.0       0.0       0.0
>    13  2
>     6  0     2.00      0.00
>     6  1     2.00      0.00
>    3.18     3.18
>
> which should be the same used in the article "Stability of NanPb (n <= 7_)
> clusters: A first-principles molecular-dynamics study" by  Luis Carlos
> Balbás and José Luís Martins (but wiht the PW functional).
> I've produced also a psedudopotential for the GGA-PBE funtional.
>
> Here is the first pat of the obtained pseudo in the abinit format:
>
> Psp for Lead   PR (LDA=pw - fully relativ.) using Improved Troullier and
> Martins method (from JL Martins psp generator)
> 82.   4.00  080307                             : zatom,zion,pspdat
> 5   7  1  0  1055  0.0                                 :
> pspcod,pspxc,lmax,lloc,mmax,r2well
>  2.233614498626119E-04        1.250000000000000E-02  2 : aa,bb,pspso
> 0   0.         0.  1  3.176472                         : 
> l=1,e99.0,e99.9,nproj,rcpsp
> 0.0  0.0  0.0  0.0                             : rms,ekb1,ekb2,epsatm
> 1   0.         0.  2  3.176472                         : 
> l=2,e99.0,e99.9,nproj,rcpsp
> 0.0  0.0  0.0  0.0                             : rms,ekb1,ekb2,epsatm
> 1   0.         0.  2  3.176472                         : 
> l=2,e99.0,e99.9,nproj,rcpsp
> 0.0  0.0  0.0  0.0                             : rms,ekb1,ekb2,epsatm
> 0.0  0.0  0.0                                  : rchrg,fchrg,qchrg
>   0 =l for pseudopotential
>  -1.7631231942344E+00 -1.7631231941348E+00 -1.7631231940327E+00
>  -1.7631231939279E+00 -1.7631231938205E+00 -1.7631231937104E+00
>  -1.7631231935975E+00 -1.7631231934817E+00 -1.7631231933630E+00
>  -1.7631231932413E+00 -1.7631231931166E+00 -1.7631231929886E+00
>  -1.7631231928574E+00 -1.7631231927230E+00 -1.7631231925850E+00
>  -1.7631231924436E+00 -1.7631231922987E+00 -1.7631231921500E+00
>  -1.7631231919976E+00 -1.7631231918413E+00 -1.7631231916812E+00
> .......
>
> I've checked the convergence in ecut and k-point grid (finding a good ecut
> value of 30 Ha and standard k-point grid composed by 60 points). My
> problems start when I try to optimize the cell parameter: the  BFGS
> optimizer finds an unrealistic cell parameter (for example 6.5 bohr instead
> of 9.4).
>
> Here is my input file for the LDA-PW fuctional:
>
> # Lead crystal
>
> # Simulation parameters
> ecut 30
> ixc 7
> occopt 7
> tsmear 0.01
> nband  8
>
> # Cell description
> acell 3*9.36
> rprim
>     0.0  0.5  0.5
>     0.5  0.0  0.5
>     0.5  0.5  0.0
> ntypat 1
> znucl  82
> natom  1
> typat  1
> xred
>   0.000   0.000   0.000
> nspinor 2
> so_psp 2
>
> # Cell optimization
> ionmov 3
> optcell 1
> tolmxf 5.0d-6
> ntime  50
> dilatmx 1.15
> ecutsm        0.5
>
> # K-points
> ngkpt 8 8 8
> kptopt        1
> nshiftk 4
> shiftk
>    0.5 0.5 0.5
>    0.5 0.0 0.0
>    0.0 0.5 0.0
>    0.0 0.0 0.5
>
> # SCF procedure
> nstep  100
> toldfe        1.0d-10
> iscf 5
>
> I got the same WARNINGS in the log file:
>
>  vtorho : WARNING -
>   For k-point number   56,
>   The minimal occupation factor is  0.029.
>   An adequate monitoring of convergence requires it to be at most 0.01_dp.
>   Action : increase slightly the number of bands.
>
> and:
>
>  BROYDEN STEP NUMBER   2
> ------------------------------------------------------
>
>  findmin : WARNING -
>   The 2nd degree equation has no positive root (choice=4).
>
>  findmin : COMMENT -
>   Will continue, since the new total energy is lower
>   than the old. Take a larger step in the same direction.
>    line minimization, algorithm   4
>                       lambda      etotal            dedv        d2edv2
>    old point       :  0.0000E+00 -3.7185833891E+00 -8.4061E-03  2.3612+159
>    new point       :  1.0000E+00 -3.7272202744E+00 -8.7001E-03  2.3240-297
>    predicted point   :        2.5000E+00 -3.7410409248E+00  0.0000E+00  
> 4.8481-308
>
> At the end of the calculation the optimised acell is 6.5 bohr.
>
> Can someone suggest a way to solve my problem?
> What I'm missing or where I'm wrong?
> Thanks a lot and best regards,
> Mauro Sgroi.
> Centro Ricerche FIAT.
> Italia.
>
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-- 
Josef W. Zwanziger
Canada Research Chair in NMR Studies of Materials
Director, Atlantic Region Magnetic Resonance Centre
Dept. of Chemistry and Inst. for Research in Materials
Dalhousie University
Halifax B3H 4J3 Canada
+1 (902) 494-1960
jzwanzig@dal.ca
http://jwz.chem.dal.ca

On sabbatical January-July 2008
Max Planck Institute for Polymer Research
Mainz, Germany