[xcrysden] PWscf structure in xcrysden problem

[W. YU]

Dear XcrysDen uses, 

I have been testing again an again for it to show my
PWscf input files. 
I met several problems
and I really appreciate if someone could help me out.

1. I tried a very simple NaCl structure input . But
when I changed the 
parameter
   Celldm(1) value, some times, it jush shows parts of
the atoms and 
sometimes 
   it works  well. I am really confused about this
"strange?" 
behaviour. The input which 
   is not shown properly is  as follows: 
   ( If I change the celldm(1) to other values such as
6.92, it does 
work.)

===========================
 &control
   calculation = 'scf',
   restart_mode = 'from_scratch',
   outdir = '/root/pwscf_workspace/tmp/',
   pseudo_dir = '/root/pwscf/pseudo/',
   tstress = .true.
 /
 &system    
    ibrav = 2, celldm(1) =6.93,
    nat= 2, ntyp= 2,ecutwfc = 25.0,ecutrho = 200.0,
/
&electron
   conv_thr =  1.0d-8
    mixing_beta = 0.7
/
ATOMIC_SPECIES
 Na 6.941  Li_VDB_LDA_SEMI.UPF 
 Cl  1.008  H.pz-van_ak.UPF 
ATOMIC_POSITIONS  
 Na 0.00 0.00 0.00 
 Cl 0.50 0.50 0.50 
K_POINTS automatic 
  8 8 8  1 1 1 
 ========================================
 2. I found if the input atomic positions are not in
the same PRIMITIVE 
    unit cell, it cannot be shown well. Is this true?
If so, I have to 
give
    all the atomic coordinates in the same PRIMITIVE
unit cell. But ]
    this is sometimes not so convenient say if we have
a BCC structure 
    of several atoms. Even a simple NaCl structure
will not work the 
way
    it is supposed to if the two atomic coordinates
(for Na and Cl) are 
    given as follow:  
====================================================
ATOMIC_POSITIONS  
 Na 0.00 0.00 0.00 
 Cl 0.50 0.00 0.00 
====================================================
    And the following is a complet input of another
BCO structure input 
    for Li2CuO2 which doesn't look the way it should
be:

=====================================================
 &control
   title = Li2CuO2 ,
   calculation = 'scf' ,
   restart_mode = 'from_scratch' ,
   outdir = '/root/pwscf_workspace/tmp/' ,
   pseudo_dir = '/root/pwscf/pseudo/' ,
   prefix = Li2CuO2 ,
   tstress = .true. ,
   tprnfor = .true. ,
 /
 &system
   ibrav = 11,
   celldm(1) = 6.9051,
   celldm(2) = 0.78188,
   celldm(3) = 2.6634,
   nat = 5,
   ntyp = 3,
   ecutwfc = 25 ,
   ecutrho = 200 ,
 /
 &electron
   mixing_beta = 0.2 ,
   diagonalization = 'cg' ,
 /
ATOMIC_SPECIES
   Li    6.94100  Li.pz-s-van_ak.UPF 
   Cu   63.55000  Cu.pz-n-van_ak.UPF 
    O   16.00000  O.pz-van_ak.UPF 
ATOMIC_POSITIONS crystal 
   Li      0.50    0.00   0.2892    0  0  0 
   Li      0.50    0.00   0.7108    0  0  0 
   Cu      0.00    0.50   0.5000    0  0  0 
    O      0.00    0.00   0.3576    0  0  0 
    O      0.00    0.00   0.6424    0  0  0 
K_POINTS automatic 
  4 4 2   1 1 1 
================================================
Sorry for this lengthy email and thanks a lot if
anybody knows the 
answer.

Best,

Wen Yu
=================

Dr. Wen Yu

Physics Department
University of Science and Technology of Beijing,
wenyu@sas.ustb.edu.cn





 
____________________________________________________________________________________
Do you Yahoo!?
Everyone is raving about the all-new Yahoo! Mail beta.
http://new.mail.yahoo.com