[Pw_forum] The overestimation of graphite lattice using vc-relax+vdW-DF

2011-07-02 Thread WANG Wei 
Is it a bug? The optimized lattice constants of vdW-DF is so different from
those of vdw1, namely,

When I set input_dft   = 'vdw-DF', I got the


  total   stress  (Ry/bohr**3)   (kbar) P=
0.03
   0.0033   0.   0.  0.05  0.00  0.00
   0.   0.0033   0.  0.00  0.05  0.00
   0.   0.  -0.0003  0.00  0.00  0.00

 CELL_PARAMETERS (alat=  4.6800)
   1.000251032   0.3   0.0
  -0.500125514   0.866242806   0.0
   0.0   0.0   2.845991200


However,  I set input_dft   = 'vdw1', I got the

  total   stress  (Ry/bohr**3)   (kbar) P=
-0.01
  -0.0002   0.   0.  0.00  0.00  0.00
   0.  -0.0002   0.  0.00  0.00  0.00
   0.   0.  -0.0007  0.00  0.00 -0.01

CELL_PARAMETERS (alat=  4.6800)
   1.292794235  -0.00090   0.0
  -0.646397196   1.119592604   0.0
   0.0   0.0   3.034982637
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[Pw_forum] The overestimation of graphite lattice using vc-relax+vdW-DF

2011-07-02 Thread Paolo Giannozzi 

On Jul 2, 2011, at 3:10 , WANG Wei wrote:

> However,  I set input_dft   = 'vdw1', I got the

'vdw1' /= 'vdw-DF', as explained in the documentation
and reprinted in the output. The correct name is 'vdw-DF'.

P.
---
Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222

[Pw_forum] The overestimation of graphite lattice using vc-relax+vdW-DF

2011-07-02 Thread WANG Wei 
Hello, everyone. As a benchmark test, I performed the vc-relax+vdW-DF
calculations for graphite. The opitimized lattice constants seem to be
unreasonable using vc-relax+vdW-DF. It is overestimated about about 29% for
a. I don't know what the problem is.

#
  total   stress  (Ry/bohr**3)   (kbar) P=
-0.01
  -0.0002   0.   0.  0.00  0.00  0.00
   0.  -0.0002   0.  0.00  0.00  0.00
   0.   0.  -0.0007  0.00  0.00 -0.01

 The maximum number of steps has been reached.
 End of BFGS Geometry Optimization
Begin final coordinates
 new unit-cell volume =450.28054 a.u.^3 (66.72469 Ang^3 )
CELL_PARAMETERS (alat=  4.6800)
   1.292794235  -0.00090   0.0
  -0.646397196   1.119592604   0.0
   0.0   0.0   3.034982637
ATOMIC_POSITIONS (crystal)
C   -0.01693   0.01693   0.25000
C0.01693  -0.01693   0.75000
C0.31648   0.68352   0.25000
C0.68352   0.31648   0.75000
End final coordinates
##



&control
   calculation = 'vc-relax'
!   restart_mode='from_scratch',
   prefix='graphite',
   tstress = .true.
   tprnfor = .true.
pseudo_dir   = "/home/wangvei/works/quantum-espresso/pseudo",
outdir   = "./",
disk_io  = 'none'
forc_conv_thr = 1.0e-3
   nstep =  45  ,
   etot_conv_thr = 1.0E-4 ,
   forc_conv_thr = 1.0D-3 ,
  iprint = 1 ,
 max_seconds = 36000 ,
  dt = 100 ,
/
&system
ibrav   = 4
celldm(1)   = 4.68
celldm(3)   = 2.70
nat = 4
ntyp= 1
occupations = "smearing",
smearing= "gaussian",
degauss = 0.002D0,
ecutwfc = 40.0
ecutrho = 200
input_dft   = 'vdw1'
/
&electrons
conv_thr= 1.0d-8
/
&ions
/
&cell
press_conv_thr  = 0.0D0
press   = 0.D0
cell_dynamics   = 'bfgs'
!cell_dofree = 'z'
/
ATOMIC_SPECIES
C   12.00   C.pbe-paw_kj.UPF
ATOMIC_POSITIONS {crystal}
 C 0.0   0.0   0.25000
 C 0.0   0.0   0.75000
 C 0.3   0.7   0.25000
 C 0.7   0.3   0.75000
K_POINTS automatic
9 9 4 0 0 0
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