Int. J. Mol. Sci. 2004, 5(11), 301-332; doi:10.3390/i5110301
Article

Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study

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Received: 24 September 2004; Accepted: 9 November 2004 / Published: 30 November 2004
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: Vertical ionization energies (IE) as a function of the conformation are determined at the quantum chemistry level for eighteen α-L-amino acids. Geometry optimization of the neutrals are performed within the Density Functional Theory (DFT) framework using the hybrid method B3LYP and the 6-31G**(5d) basis set. Few comparisons are made with wave-function-based ab initio correlated methods like MP2, QCISD or CCSD. For each amino acid, several conformations are considered that lie in the range 10-15 kJ/mol by reference to the more stable one. Their IE are calculated using the Outer-Valence-Green's-Functions (OVGF) method at the neutrals' geometry. Few comparisons are made with MP2 and QCISD IE. It turns out that the OVGF results are satisfactory but an uncertainty relative to the most stable conformer at the B3LYP level persists. Moreover, the value of the IE can largely depend on the conformation due to the fact that the ionized molecular orbitals (MO) can change a lot as a function of the nuclear structure.
Keywords: vertical ionization energies; amino acids; ab initio calculations
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MDPI and ACS Style

Dehareng, D.; Dive, G. Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study. Int. J. Mol. Sci. 2004, 5, 301-332.

AMA Style

Dehareng D, Dive G. Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study. International Journal of Molecular Sciences. 2004; 5(11):301-332.

Chicago/Turabian Style

Dehareng, Dominique; Dive, Georges. 2004. "Vertical Ionization Energies of α-L-Amino Acids as a Function of Their Conformation: an Ab Initio Study." Int. J. Mol. Sci. 5, no. 11: 301-332.


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