incorrect number of frequencies in vibrational analysis

Natalie Schieber natalie.... at colorado.edu
Mon May 8 20:45:02 CEST 2017


Dear all,

I am trying to obtain the vibrational frequencies of a periodic system of 
four benzene molecules. When I run the vibrational analysis with no 
restriction, I obtain the correct number of frequencies (141), but some of 
them are negative. However, when I restrict the range of the search, I 
obtain positive wavenumbers, but more frequencies than should be physically 
present (152). When I try to run the vibrational analysis with tighter 
convergence but no range, I get an error.  The relevant part of the input 
is below. Any help on obtaining 141 positive numbers is appreciated!

&VIBRATIONAL_ANALYSIS
&MODE_SELECTIVE
EPS_MAX_VAL 0.0000000005
EPS_NORM 0.00000002
&END MODE_SELECTIVE
&END VIBRATIONAL_ANALYSIS

Returns an error:  no frequency, range or involved atoms specified  

&VIBRATIONAL_ANALYSIS
&END VIBRATIONAL_ANALYSIS

returns 141 wavenumbers with negatives


&VIBRATIONAL_ANALYSIS
&MODE_SELECTIVE
EPS_MAX_VAL 0.0000000005
EPS_NORM 0.00000002
RANGE 0 50000
&END MODE_SELECTIVE
&END VIBRATIONAL_ANALYSIS

returns 152 positive numbers




Best,
Natalie Schieber
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