Gauge-including atomic orbital applications

The 13C chemical shift contour map for the Cp carbon of the L-alanine residue in peptides and polypeptides was made as a function of the dihedral angles(, W) by using the experimental data. Also, the corresponding calculated map was made by using the ab initio coupled Hartree-Fock method with the gauge included atomic orbitals(GIAO-CHF). From these results, it was found that the calculated map explains the chemical shift behavior of the a-helix and p-sheet forms in poly(L-alanine) and some proteins. This suggests that the calculated map is applicable to the structural analysis of proteins with complicated structure. 

R. Fukuda, M. Hada, H. Nakatsuji. Quasirelativistic theory for the magnetic shielding constant, n. Gauge-including atomic orbitals and applications to molecules. J. Chem. Phys., 118(3) (2003) 1027-1035. 

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