On Tue, 5 Apr 2005, navaratnarajah kuganathan wrote:
| I am Navaratnarajah Kuganathan am a DPhil Student working on Nanotubes
| and Compounds using SIESTA in Oxford.I am now doing calculation on bulk
| HgI2.I have used Fractional Coordinates according to the previous calculation
| by researchers.I observed Density Matrix Converged to Zero for initial
| (CG Move=0 ,within 50 SCF cycle).But it takes more than 200 for
| CG move =1 ,2 ,3 etc. and difficult to converge. I am herewith attaching
| the output file for my calculation. I would like to clarify
|
| 1.I have given correct fractional coordinates for HgI2.
| For My electronic structure calculation, is it must to specify
| CG steps = 50 or 100 etc.....for geometry optimisation.
| I think if we put correct values of Lattice parameters
| and fractional coordinates,no need to optimise geometry????.
|
| I would appreciate if you could help in this regard.
Hallo,
the answer depends on whether you really need to optimize geometry
(then you must do it),
or you want just electronic structure for a fixed lattice,
"correct values of Lattice parameters and fractional coordinates",
in which case CG=0 is fine.
Anyway, your calculation is probably wrong because you use
AtomicCoordinatesFormat Fractional
%block AtomicCoordinatesAndAtomicSpecies
-1.0925 -1.0925 -3.11000 1
1.0925 1.0925 3.11000 1
...
that is weird (albeit legal) because fractional coordinates are supposed
to be [ 0, 1 ]. Your cartesian coordinates (at the beginning of
each CG move) are
outcoor: Atomic coordinates (Ang):
-4.77422500 -4.77422500 -38.68837388 1 Hg 1
4.77422500 4.77422500 38.68837388 1 Hg 2
...
that is probably not what you want, with your
LatticeConstant 4.370 Ang
and LatticeParameters
1.00 1.00 2.84668 90. 90. 90.
Moreover for structure relaxation in a crystal you'd need more
k-points than one, and probably higher Mesh cutoff than default value.
Good luck,
Andrei Postnikov
+-- Dr. habil. Andrei Postnikov ----- Tel. +49-541-969.2377 -- Fax .2351 ---+
| Institut fuer Festkoerperforschung - FZ Juelich, D-52425 Juelich, Germany |
+-- [EMAIL PROTECTED] --------- http://www.home.uni-osnabrueck.de/apostnik/ --+
