Accession Number : ADA305370

Title :   Density Functional and MP2 Calculations of Spin Densities of Oxidized 3-Methyl Indole. Models for Tryptophan Radicals.

Descriptive Note : Final rept. Jan 95-Jan 96,

Corporate Author : ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s) : Jensen, G. M. ; Goodin, D. B. ; Bunte, S. W.

PDF Url : ADA305370

Report Date : MAR 1996

Pagination or Media Count : 40

Abstract : Ab initio calculations have been carried out on 3-methyl indole, and the cation and neutral radicals of 3-methyl indole, using Density Functional Theory (DFT), the Becke3-Lee-Yang-Parr functional, and the 6-31G*, 6-31+G*, 3-21G*, and TZ2P basis sets. Optimized geometries, vibrational frequencies and, for the radicals, atomic spin densities are calculated. The latter are compared to experimental spin densities recently determined for the tryptophan-191 radical of compound ES of the enzyme cytochrome-c-peroxidase. The DFT spin densities for the cation radical of 3-methyl indole are in excellent agreement with the data for the tryptophan-l91 radical, which supports the conclusion that the tryptophan radical is a cation radical. The results are compared to calculations using second-order Moller-Plesset theory (MP2) and the 6-31G** basis set. The MP2 spin densities are in significantly worse agreement with the experiment spin densities. jg p3

Descriptors :   *COMPUTATIONS, *QUANTUM CHEMISTRY, *METHYL RADICALS, *SPIN STATES, *CHEMICAL RADICALS, *INDOLES, *TRYPTOPHAN, FREQUENCY, CATIONS, DENSITY, VIBRATION, OPTIMIZATION, NEUTRAL, ELECTRONS, OXIDATION, GEOMETRY, SOLID STATE CHEMISTRY.

Subject Categories : Organic Chemistry
      Physical Chemistry
      Quantum Theory and Relativity

Distribution Statement : APPROVED FOR PUBLIC RELEASE