[Wien] Volume of BP unit cell.

[Luciano Ortenzi]

Dear all,

Before calculating the bandstructure of black phosphorus at ambient  
pressure (space group 64_Cmca)
I run a scf cicle and check for the unit cell volume (grep :VOL *.scf).
It turns out that the volume of the unit cell is half of the value I expected.
Namely

:VOL  : UNIT CELL VOLUME =     501.04679

while the product of the lattice parameters (the system is orthorhombic)

is a*b*c=1002,09359 Bohr^3.

Here is the struct file.
Best!

Title
CXY LATTICE,NONEQUIV.ATOMS:  1 64_Cmca
MODE OF CALC=RELA unit=ang
   6.264445 19.558673  8.178738 90.000000 90.000000 90.000000
ATOM  -1: X=0.00000000 Y=0.10240000 Z=0.08000000
           MULT= 4          ISPLIT= 8
       -1: X=0.00000000 Y=0.89760000 Z=0.92000000
       -1: X=0.00000000 Y=0.60240000 Z=0.42000000
       -1: X=0.00000000 Y=0.39760000 Z=0.58000000
P          NPT=  781  R0=0.00010000 RMT= 2.08        Z: 15.0
LOCAL ROT MATRIX:    0.0000000 0.0000000 1.0000000
                      1.0000000 0.0000000 0.0000000
                      0.0000000 1.0000000 0.0000000
    8      NUMBER OF SYMMETRY OPERATIONS
-1 0 0 0.00000000
  0-1 0 0.00000000
  0 0-1 0.00000000
        1
-1 0 0 0.00000000
  0 1 0 0.00000000
  0 0 1 0.00000000
        2
  1 0 0 0.00000000
  0-1 0 0.00000000
  0 0-1 0.00000000
        3
  1 0 0 0.00000000
  0 1 0 0.00000000
  0 0 1 0.00000000
        4
-1 0 0 0.00000000
  0-1 0 0.50000000
  0 0 1 0.50000000
        5
-1 0 0 0.00000000
  0 1 0 0.50000000
  0 0-1 0.50000000
        6
  1 0 0 0.00000000
  0-1 0 0.50000000
  0 0 1 0.50000000
        7
  1 0 0 0.00000000
  0 1 0 0.50000000
  0 0-1 0.50000000
        8



-----------------------------------------------
Luciano Ortenzi, PhD
ISC-CNR
c/o Department of Physics
University of Rome "La Sapienza"
P.le A. Moro 5, 00185 Rome (Italy)
Tel: +39-06-49913489
e-mail: Luciano.ortenzi at isc.cnr.it
web page: http://www.isc.cnr.it/staff-members/luciano-ortenzi/
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