eps(mixed) = eps(water)*0.1 + eps(DMSO)*0.9
where eps(water) and eps(DMSO) can be directly found from Gaussian manual.

Best,

Tian

I would like to calculate (eps=??) for mixed solvents such as binary solvent (DMSO: Water=9:1 v/v).

Best regards
Behnam Dehbandi

Static dielectric constant is not calculated by Gaussian, but should be specified by user in Gaussian input file. As you know volume ratio of different solvents and static dielectric constant of each kind of pure solvent, you can directly estimate static dielectric constant of mixed solvent.

Best,

Tian

Dear prof.Tian Lu

How can I calculate the mixture of solvent in gaussian? How will I specify the mixture of solvents in gaussian inputs? also, How can I  calculate free Gibbs  G salvation with different mole fractions?

Best regards
Behnam Dehbandi

Dear Behnam Dehbandi,

You can specify mixed solvent by customizing static dielectric constant, for example

#p B3LYP/6-31G* scrf=read

test

0 1
 C                  0.00000000    0.00000000   -0.52887900
 H                  0.00000000    0.93777000   -1.12367000
 O                  0.00000000    0.00000000    0.67757700
 H                  0.00000000   -0.93777000   -1.12367000

eps=18.5

Where 18.5 is static dielectric constant of mixed solvent, which can be estimated as dielectric constant of each kind of solvent weighted by their volumes.

I don't well understand your second question.

Best,

Tian

How can I calculate the mixture of solvent in gaussian? How will I specify the mixture of solvents in gaussian inputs? also, How can I  calculate free Gibbs  G salvation with different mole fractions?

Best regards
Behnam Dehbandi

Can I use out =wfn with job type energy and pop=(full,nbo) in gaussian to generate the .wfn file for NCI analysis?

You can.

My another question is
While running the job with type 'energy' and counterpoise=2, can I add out=wfn to get the .wfn file which will be used for Non-covalent interaction (NCI) analysis  in Multiwfn? Or do I have to run two separate jobs- one for counterpoise=2 and another for wfn file which will be used for Non-covalent interaction (NCI) analysis ?

Please do not try to produce wavefunction file using counterpoise task. Counterpoise task should only be used to evaluate BSSE correction energy and corrected interaction energy.

I had a question regarding BSSE corrected binding energy.
I want to calculate BSSE corrected binding energy of say A+B----> AB
I have the energies of molecules A, B and complex AB.
So, del E' = E(AB) - E(A)- E(B).
I then run a job in gaussian with type 'energy' and counterpoise=2. The .log file contains  'BSSE energy =       0.015554255487'
Will the BSSE corrected binding energy be delE'+  0.015554255487 ?

It is correct.

By the way, if your Gaussian version is not too old, counterpoise task will directly give you "complexation energy", it is just the interaction energy corrected by BSSE.