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Re: Long time optimization

Amir Nasser Shamkhali
amir_n_shamkhali@yahoo.com

On Fri Feb 25 '11 3:35pm, Khimich wrote
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>Sometimes the optimization requires a lot of iterations. For example, if there is SO2R - group, for some dihedral angles rotate very slowly. Is there any way to speed up the calculation?
>

Dear Khimich
I see your input structure is too far from an actual organic compound. For instance, the C-C bond length in the ring is 2.6 angstrom. Thus, before the final calculation use one or both of the following methods:
1) Use an appropriate molecular editor software to make a reasonable input geometry. See the "Related" page of this site.
2) For organic compounds, use a previous optimization with a fast semiemprical method such as AM1, PM3, MNDO and etc. and take this optimized structure as an input for final optimization by DFT.

Best Wishes

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