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Optimization followed by vibrational analysis (numerical) with CCSD

Posted: 18 Nov 2017, 06:56
by ankit7540
Hello all,
I can easily run independent optimization and vibrational analysis (using numerical derivatives) using CCSD using two separate calculations.
However, I wonder if it is possible to combine these. Hence, first run optimization, and if the optimization succeeds then do vibrational analysis, (both under CCSD).

In my approach, I set tight optimization parameters and tight SCF convergence. Most of the times, optimization is successful. However, vibrational analysis does not proceed. I tried this with water and I get error about missing AOWOINT file, and I am unable to resolve this.

Could anyone drop a hint. Thank you. :-)

Re: Optimization followed by vibrational analysis (numerical) with CCSD

Posted: 21 Nov 2017, 12:52
by magnus
I think your problem is that you're using **PROPERTIES which doesn't work with CC.

Re: Optimization followed by vibrational analysis (numerical) with CCSD

Posted: 22 Nov 2017, 13:16
by ankit7540
Hello,
With the **PROPERTIES keyword the .VIBANA analysis works fine as shown in the attached output file ( and the program gave me the hessian as I asked for).
ccsd_freq_water_singleOpt_DZ.out
Frequency analysis only with **PROPERTIES and .VIBANA
(63.5 KiB) Downloaded 375 times

Re: Optimization followed by vibrational analysis (numerical) with CCSD

Posted: 22 Nov 2017, 13:30
by magnus
I think what you are getting from the PROPERTIES module is just based on HF and not CC. If you look at chapter 28 in the manual, you will see that it says HF, SOPPA, and MCSCF molecular properties. To be sure that this is the case, you can try to run a new calculation using the same input, but only with .HF and remove all CC input parts.

Re: Optimization followed by vibrational analysis (numerical) with CCSD

Posted: 26 Nov 2017, 06:19
by ankit7540
Hello,
You are correct. I confirmed that the program does the vibrational analysis using HF and not the CC wavefunctions. Thanks for the clarification.

Ankit