computational chemistry: I want to make the base overlap corrections for the dichloroacetyl chloride dimer. I put the following sentence to run the calculation in Gaussian: frec B3LYP/6-311++G** Test but the calculation dies. What could be the problem?
Well,
First of all, shouldn't it be 'freq' instead of 'frec'?
Guessing that you just misspelled it here, I'd suggest the counterpoise correction from Boys and Bernardi to obtain data like intermolecular interaction energy, but the approach on BSSE depends on what kind of data you are looking for, applying a posteriori correction shouldn't be a blackbox choice.
'counterpoise' keyword is used to apply Boys and Bernardi method .
You can read more about counterpoise here: Article How does basis set superposition error change the potential ...
And here:
Article The Calculation of Small Molecular Interactions by the Diffe...
Luciana Tamone
Dear Luciana,
Below you can comprehensively find how a BSSE calculation should be performed:
Suppose that you are going to calculate interaction energy (I.E.) for intermolecular hydrogen-bonded H3N...HOH complex.
Initially, you should optimize this system at a desirable computational level such as B3LYP-D3(BJ)/def2-TZVPP. Such optimization should be followed by a frequency calculation at the same level to ensure there is not any imaginary frequency. Now, you can save the optimize geometry and attempt to calculate I.E. Note that calculation of I.E. demands highly accurate computational levels. In this sense, while CCSD(T) calculations extrapolated toward CBS (complete basis set) are very common, you can also employ CCSD(T)/jul-cc-pVTZ level. In addition, while it is preferred to use aug-cc-pVTZ instead of jul-cc-pVTZ, very recently and in DOI: 10.1002/jcc.26068, we showed that jul-cc-pVTZ is as robust as aug-cc-pVTZ and can be used to obtain very accurate values of I.E. in a less expensive cost.
To reach this purpose, taking the optimized structure of complex, your Gaussian input should be as follows:
# ccsd(t)/jul-cc-pvtz counterpoise=2
Title Card Required
0 1,0 1,0 1
O -0.03836200 1.54613400 0.00000000 1
H 0.06356500 0.57566500 0.00000000 1
H 0.85354600 1.90026300 0.00000000 1
N -0.03836200 -1.37627100 0.00000000 2
H -1.03728700 -1.54652400 0.00000000 2
H 0.34780000 -1.83229000 0.81779500 2
H 0.34780000 -1.83229000 -0.81779500 2
Note that there are three 0 1 which indicate charge and total multiplicity of complex, monomer 1, and monomer 2, respectively. In addition, as you can see at the end of each line within molecular specification, atoms belonging to monomer 1 are characterized with number 1 while those of monomer 2 with number 2.
Now, you can run this job.
After completion and at the end of output file, you can find what you are looking for:
BSSE energy = 0.000638404757
complexation energy = -6.62 kcal/mole (raw)
complexation energy = -6.21 kcal/mole (corrected)
The first value is the BSSE energy in a.u. The second value (raw) is the uncorrected value of I.E (No CP-I.E.) corresponded to E(complex)-E(monomer 1)-E(monomer 2).
The third value (corrected) is the CP-corrected I.E. associated with E(complex)-E(monomer 1)-E(monomer 2)+BSSE.
Note that this method of I.E. calculation does not consider deformation energy (DE). DE, particularly for small and rigid monomers, is very small and can safely be ignored (I suggest you to carefully read the above-mentioned DOI). Meanwhile, such a complete report is provided since Gaussian 16. I think (I am not sure, please check it) Gaussian 09 is not able to provide CP-corrected I.E. and you have to do some calculations manually.
I hope this can help you.
Sincerely,
Saeed
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