[CPMD-list] negative frequencies obtained after vibrational analysis

[Alexandr Isayev]

Axel,
Nagesh

AK> alex, are you sure, that negative frequencies this hight are not suspicious??

I did not say that they are not suspicious :) I just pointed out for a
difference with the standard codes. In fact, they are *very suspicious*!
If you subtract those 6 modes, there are tree more left with v around
zero.

>can you please let me know whether my system has obtained ground state

Nagesh, even more! Did you visualize geometry after optimization?
If you have background in chemistry you will immediately see,
why your frequencies are odd. Your structure is far from minimum!

Finally, one advise from my experience. CPMD code is stands for
*molecular dynamics* and related tasks. For your complex non periodic system
it is really difficult to get good structure and good frequencies
(especially using numerical FD approach) in plane waves. You will do this MUCH
more faster using conventional code (Gaussian, NWchem, etc) and
analytical frequencies.

Hope this will help,
Alexandr




-------------------------------------------------------
Alexandr Isayev,
Graduate Research Assistant, and System Administrator
@ Computational Center for Molecular Structure
and Interactions (CCMSI),
Jackson State University,
Jackson, MS USA
   Tel:  +(601) 979-1134
e-mail:  alex(at)ccmsi.us
   Web:  http://www.ccmsi.us
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