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### What is the unit of optical rotation in Dalton outfile

Posted: **11 May 2017, 13:29**

by **keyares**

I have calculated the optical rotation of a compound, and the result is showed below.

Frequency 0.077318 au = 589.300000 nm

Beta (London) : -2.321026

Optical rotation (London): -501.026215

My experimental data is [α]D=-10

Therefore, I think the unit in the outfile is difference from the unit of specific rotation.

I will be grateful if someone can tell me the unit in the outfile.

Thanks a lot.

Best regards

### Re: What is the unit of optical rotation in Dalton outfile

Posted: **11 May 2017, 22:09**

by **kennethruud**

Hi!

Without telling us anything about your calculation nor the molecule, it is very difficult to give any indication of what the problem is. Calculating accurate optical rotations is challenging, and the results may depend strongly on factors such as basis set, exchange-correlation functional (or your choice of wave function model), solvent effects, conformational flexibility and averaging, and zero-point vibrational effects.

Thus, you need to at least provide an output file and a molecular structure, and we can maybe assist in excluding some sources of error that can in part or in full explain the difference you observe compared to experiment.

Best regards,

Kenneth

### Re: What is the unit of optical rotation in Dalton outfile

Posted: **14 May 2017, 15:12**

by **keyares**

Thank you very much for your kind reply.

I know there are many factors influencing the results of optical rotation calculation.

I am doing the calculation following the method reported in the literature J. Phys. Chem. A 2000, 104, 1039-1046.

The first problem for me is that I don't know the unit of the calculated results. Although I have the sign, I wish I can also compare the value with the experimental data.

I have read the formula of calculating the optical rotation value from Beta value. But I didn't figure out the unit of the final results.

The outfile is attached.

All the best for you.

Wen-Xuan Wang