Frequency calculation again
Posted: Fri Jul 01, 2005 7:17 am
Dear Sir
I have performed several calculation on alkane and cikloalkane. I found some very strange behaviour.
If I begin the optimalisation from a godd geometry
(optimised by gaussian with good basis) I got 2 big negativ frequency(around 8-900 cm-1) If I change the geometry according the normal vektor of these mode I got one or two every strange frequencies.(around 1600-1700 cm-1)
I have already try to increase the accuracy, the box size, using the ISYM command.
Can anbody give me som advice?
(If I performed the calculation on surface, I got quite reasonable frequncies)
imre
I have performed several calculation on alkane and cikloalkane. I found some very strange behaviour.
If I begin the optimalisation from a godd geometry
(optimised by gaussian with good basis) I got 2 big negativ frequency(around 8-900 cm-1) If I change the geometry according the normal vektor of these mode I got one or two every strange frequencies.(around 1600-1700 cm-1)
I have already try to increase the accuracy, the box size, using the ISYM command.
Can anbody give me som advice?
(If I performed the calculation on surface, I got quite reasonable frequncies)
imre