How do I reduce the symmetry along C axis ?

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SangLee · #1 Post by **SangLee** » Mon Mar 22, 2010 5:51 am

Dear Colleagues in the Forum:

I want to reproduce the electronic structure of KCuF3 using vasp. Some papers mentioned that the ground magnetic state is an orbitally ordered state and an insulator, and the state can only be obtained with LSDA + U (or GGA + U ) and WITHOUT THE USE OF SYMMETRY along C axis (PRB,52, 5467[1995]). I could not reproduce the results even with the ISYM=0 option. The ISYM=0 option seems to remove the symmetries along the A and B axis but not the symmetry along C axis.

How do I reduce or remove the symmetry along C axis ?

Thank you.

With Best Regards,

Sang

#2 Post by **admin** » Mon Mar 22, 2010 4:04 pm

ISYM=0 reduces ALL symmetrization except time-reversal (C_1), but you can of course reduce your symmetry by setting ISYM=-1, or 'by hand', by displacing one of the atoms from its high-symmetry position in POSCAR slightly (by a mÃ…). the system will relax to its equilibrium geometry

xianfeng · #3 Post by **xianfeng** » Thu Jun 03, 2010 8:50 am

Dear admin
What is the meaning of ISYM=-1, I couldn't find any information in the vasp manual, please give a detailed discription.
Thanks a lot.
xianfeng

#4 Post by **admin** » Thu Jul 01, 2010 8:52 am

ISYM = -1 lifts the time-reversal symmetry