Dear Yong Liu,
As far as I understood you want to keep a=b!=c and angles 90, 90 ,90
after relaxation, don't you? Then you don't need any geometry
constraints, just make variablecell=true calculations. To my
experience, the angles will not change or change a little (in my case
smth like 89.999). Then use obtained lattice parameters and
coordinates and repeat the relaxation but with VariableCell = false.
Manually change angles to 90 90 90, if they were changed in previous
run. This second calculation will relax atomic cooredinates only, not
unit cell.
On 27/03/07, Yong Liu <[EMAIL PROTECTED]> wrote:
Dear all:
I'd like to apply a restrict geometry optimization considering the
symmetry of the system, but from the manual I do not find the useful
parameters. For instance, How can I fully optimize tetragonal PbTiO3 (P4mm,
No.99) which has a=b!=c, Pb(0,0,x1),
Ti(0.5,0.5,x2),O1(0,0.5,x3),O2(0.5,0,x3),O3(0.5,0.5,x4). I'm afraid that
'GeometryConstraints' is not good enough to deal with this work since the
constrainsts of this parameter are not implemented, as mentioned in the
manual.
Is there any parameters provide a mode of structural relaxtion taking
into account the symmetry of the system and how to use them? Thanks a lot in
advance.
--
Best regards.
-------------------------------------------------------------------------------------
Liu, Yong, Ph D
Institute of Inorganic Materials,
Department of Materials Science and Engineering,
Zhejiang University,PR China
--
Yurko Natanzon
PhD Student
Henryk Niewodniczański Institute of Nuclear Physics
Polish Academy of Sciences
ul. Radzikowskiego 152,
31-342 Kraków, Poland
Email: [EMAIL PROTECTED], [EMAIL PROTECTED]
