I tried to optimise a hexagonal unit cell.
but after optimisation its xred values are totally changed, but this has not happen in case of fcc, bcc (neglisible variation).
is there any input variable using that we can fixed the values of reduced coordinates of atoms in optimisation.
can anyone give some information related to this.
Ashish
optimisation problem in xred
Moderator: bguster
-
david.waroquiers
- Posts: 138
- Joined: Sat Aug 15, 2009 12:45 am
Re: optimisation problem in xred
Hello,
If the optimization gives something completely different, your initial positions might be wrong. What's the system you are studying and what's your input file ?
Btw, it is possible to fix the unit cell and let the atomic positions relax (or variations, like let the unit cell vary in one direction but in the two others ...). It is also possible to fix some of the atoms in the cartesian positions (natfix iatfix, ... variables). Note also that if your system has symmetries, the optimization will keep these symmetries.
David
If the optimization gives something completely different, your initial positions might be wrong. What's the system you are studying and what's your input file ?
Btw, it is possible to fix the unit cell and let the atomic positions relax (or variations, like let the unit cell vary in one direction but in the two others ...). It is also possible to fix some of the atoms in the cartesian positions (natfix iatfix, ... variables). Note also that if your system has symmetries, the optimization will keep these symmetries.
David