### different occopts give different qualitative result

Posted:

**Wed Jan 23, 2019 9:44 am**Dear all,

I've been calculating a system with two slightly different structures, say structures A & B. The first set of calculations using occopt 6 and resulted in the total energy of A (EA) smaller than the total energy of B (EB). However, when I use occopt 7 the results show that EB < EA.

Has anyone experienced this before? Can anyone tell me which occopt is better to use?

Thanks!

I've been calculating a system with two slightly different structures, say structures A & B. The first set of calculations using occopt 6 and resulted in the total energy of A (EA) smaller than the total energy of B (EB). However, when I use occopt 7 the results show that EB < EA.

Has anyone experienced this before? Can anyone tell me which occopt is better to use?

Thanks!