Frequency Problem

Questions
#1

In frequency calculation more than one imaginary ( 3 or 4 frequencies) show ; how to reduce number of imaginary frequency ?

#2

@VishvaJeet Can you provide an input file so I can better assist you?

#3

$molecule
0 2
Cl 0.00000000 0.00000000 0.00000000
O 0.00000000 0.00000000 1.57404324
H 1.41001707 0.00000000 1.95054078
O 2.43956233 -0.08720061 2.08148770
H 2.60371979 -0.55886311 2.90282417
H 2.95996073 -0.63735095 1.07534391
O 3.38727550 -1.14266971 0.13820650
H 3.80969208 -0.50833861 -0.45117704
H 2.59947821 -1.58959509 -0.39053043
Cl 1.12463650 -2.19328724 -1.21766191
$end

$rem
jobtype ts
method ccsd
basis aug-cc-pvdz
$end

$molecule
read
$end

$rem
jobtype freq
basis aug-cc-pvdz
method ccsd
$end

#4

@VishvaJeet, I started to run this job and realized a potential issue with your input.
I believe you are trying to run a jobtype = ts transition state optimization followed by a jobtype = freq frequency calculation. If that is the case this input is incorrect for that, you need to add @@@@ in between the inputs. Otherwise the job will only run the last section jobtype = ts which could explain the multiple imaginary frequencies since the molecule was never optimized and the jobtype = ts was not performed.

$molecule
0 2
Cl 0.00000000 0.00000000 0.00000000
O 0.00000000 0.00000000 1.57404324
H 1.41001707 0.00000000 1.95054078
O 2.43956233 -0.08720061 2.08148770
H 2.60371979 -0.55886311 2.90282417
H 2.95996073 -0.63735095 1.07534391
O 3.38727550 -1.14266971 0.13820650
H 3.80969208 -0.50833861 -0.45117704
H 2.59947821 -1.58959509 -0.39053043
Cl 1.12463650 -2.19328724 -1.21766191
$end

$rem
jobtype ts
method ccsd
basis aug-cc-pvdz
$end

@@@@

$molecule
read
$end

$rem
jobtype freq
basis aug-cc-pvdz
method ccsd
$end
#5

@pfmclaug - the GUI for this discussion forum eats the “@@@” symbols if you just copy/paste, so that might have been in the users’ input. Need to use the formatted text box (like Peter did) to avoid this.