Dear SIESTA Users,
I am trying to perform calculations on bulk CoI2 (cobalt diiodide) which
has the Cd(OH)2/CdI2-type structure (P3-m1 space group).
It is a hexagonal close pack (HCP) with the ABAB... structure. I have
performed many calculations on fcc, bcc and cubic structures, but I cannot
work out how to input the coordinates and lattice vectors for this HCP
structure.
I have tried several variations of coordinates and lattice
vectors/parameters, including:
==========================================
LatticeConstant 3.985 Ang # a=b=3.985Ang, c=6.664Ang. (c/a =
1.6723 Ang) ref: S.R.Kuindersma,Physica (1981) 111, 231
%block LatticeParameters
1.000 1.000 1.6723 90.000000 90.000000 120.000000
%endblock LatticeParameters
#%block LatticeVectors # taken from Navy
website: http://cst-www.nrl.navy.mil/~mehl/phonons/hcp/
# 0.500 -0.866025 0.000000 # 1/2, -1/2 3^1/3, 0
# 0.500 0.866025 0.000000 # 1/2, 1/2 3^1/2, 0
# 0.000 0.000000 1.672271 # 0, 0, c/a
#%endblock LatticeVectors
AtomicCoordinatesFormat Fractional
AtomCoorFormatOut Ang
%block AtomicCoordinatesAndAtomicSpecies
0.00000000 0.00000000 0.00000000 1
0.33333333 0.33333333 0.25000000 2
0.66666667 0.66666667 0.75000000 2
%endblock AtomicCoordinatesAndAtomicSpecies
========================================
Could someone perhaps explain to me what I am doing wrong and how/where to
get appropriate coordinates and lattice vectors from?
Thanks in advance
Emma
