# How can I perform calculations including the relativistic approximation SC-ZORA and solvent approximation COSMO in Gaussian 09?

I am working on transition metal centered oganometallic complexes.

How can I apply or run the relativistic and non relativistic zero-order regular approximation (SC-ZORA) using Gaussian 09 in a DFT calculation?

I would also like to know about the process of performing COSMO analysis in Gaussian.

I have only available Gaussian 09 package for this purpose.

Gaussian can’t effectively treat relativistic effects (look up integral=dkh [1] and try its limited use. AFAIK you can only have 50 parameters in internal coordinates which is not very realistic for common molecules today.) and has no ZORA implemented. It is also not able to do COSMO PCM calculations. Instead one would use other PCM schemes, e.g. IEFPCM which is the default in Gaussian.

So can you perform your calculations with Gaussian 09? Unfortunately not.

Instead, you should change to other programs that fit your needs better. As it is free for academic use [2], you can have a look at ORCA and if it fits to your needs.

[1] http://gaussian.com/integral/
[2] read the licence carefully, it is quite strict

• Thank you very much Mr. Martin for more clarification in questions and thanks a lot to pH13 - Yet another Pjilipp and paracetamol for answer and further modifications. I just like to know another thing as I am a novice in the sector. What is the difference between the relativistic and non-relativistic approximation, I mean, if I use Gaussian 09 program with integral =dkh0 and cpcm continuum polarization field instead of COSMO? I am expecting a comment. Of course I shall check for ORCA whether I can use it suitably or not now. Thank you again for your kind attention and suggestions. – Keshab K. Adhikary Jul 18 '17 at 8:33
• pH13 Yet another Philipp, Thank you. But your Ref [2] is not linked properly. Anyway I am checking and will inform later. Thank you very much for your kind suggestion and help with valuable comments. – Keshab K. Adhikary Jul 18 '17 at 10:30
• @KeshabK.Adhikary The second is only a comment but no link. – pH13 - Yet another Philipp Jul 18 '17 at 11:13
• Regarding your two questions; I think you can either search on the site for solutions to that or ask it as two new questions. First about the difference between relativistic and non relativistic treatment (of your system, give an example on at least a very similar system ... if a similar question does not exist) and another question on the difference between COSMO and CPCM. – pH13 - Yet another Philipp Jul 18 '17 at 11:16
• More of a side-note, but the most recent version of ORCA no longer supports COSMO by the way. – Argon Jul 18 '17 at 14:52