Re: CCL:solvation effects over amino acid conformers



I cannot really answer this question for the solvation methods in Gaussian,
 but there was a study on this subject by a Danish
 group:
 ?Conformational analysis of cyclic acidic a-amino acids
 in aqueous solution - an evaluation of different continuum hydration
 models."
 by Peter Aadal Nielsen, Per-Ola Norrby, Jerzy W. Jaroszewski, and Tommy
 Liljefors,
 It was intended for JACS. But I think it is published yet only in the thesis of
 Peter Aadal Nielsen.
 For several ionic cyclic amino acids the population of several conformations was
 carefully measured by NMR and the relative
 poulations were converted to free energy differences. Then different solvation
 methods have been tested whether they are able to
 reproduce the free energy differences.
 Method            	Solvent           rms         rms (4 points)     Max Dev
                      	 Model         (kJ/mol)        (kJ/mol)        (kJ/mol)
 AM1                 	SM5.4A            4.6              5.6              9.2
 PM3                 	SM5.4P            13.6            16.2             20.5
 AM1                 	SM2.1             7.4              9.0             16.7
 HF/6-31+G*    		C-PCM             3.1              3.8              5.9
 HF/6-31+G*     		PB-SCRF           4.7              5.8              8.8
 AMBER*          	GB/SA            13.2             16.2             24.3
 MMFF               	GB/SA            18.5             19.9             31.4
 BP-DFT/TZVP  		COSMO-RS         2.2               2.6              4.8
 COSMO-RS was evaluated as a blind test !!!
 Here COSMO was done with Turbomole, using BP91 and TZVP basis set. After that
 the COSMO-RS model was applied, using the program
 COSMOtherm from COSMOlogic.
 Regards
 Andreas
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