Re: CCL:Freezing atoms-modredundant

Thanks for the replies. I think I found the problem. I needed the Nosymm keyword for the optimization to work properly. Thanks again!
 Aaron Deskins wrote:
 Hello all,
I have (hopefully) a relatively simple question. I'm trying some simple test calculations using Gaussian 98, but am running into a little problem freezing atom positions. Essentially I want to freeze a few atoms, and allow others to relax. Below is a test file. The problem I see is that the geometry optimization algorithm moves all atoms to the same location on first pass and subsequently causes the program to crash. I've tried different atoms and arrangements with no luck. Any suggestions? Thank you
 # opt(maxcycle=200,modredundant) hf/lanl2dz scf(diis,maxcycle=300)
 Title Card Required
 0  3
 c 0.0000000000 0.0000000000 0.0000000000
 c 2.7718585823 0.0000000000 0.0000000000
 c 0.0000000000 2.7718585823 0.0000000000
 c 2.7718585823 2.7718585823 0.0000000000
 1 f
 2 f
 3 f
 Aaron Deskins
 Graduate Student
 Chemical Engineering
 Purdue University