On the use of the quasi-Gaussian entropy theory in systems of polyatomic flexible molecules
Amadei A, Iacono B, Grego S, Chillemi G, Apol MEF, Paci E, Delfini M, Di Nola A
JOURNAL OF PHYSICAL CHEMISTRY B
105 (9): 1834-1844 MAR 8 2001

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Abstract:

In this article we show how the quasi-Gaussian entropy (QGE) theory can be used to treat systems of polyatomic flexible molecules, where the usual semirigid description is not always appropriate. We describe a completely general derivation of the QGE theory which does not make use of any semirigid approximation, and therefore it is very suited for large and flexible molecules. Using molecular dynamics simulations of flexible molecules in vacuo, we investigated the ability of the theory to describe intramolecular energy fluctuations and conformational equilibria of purely classical molecules in the ideal gas condition. Results show that the gamma state level of the theory and its generalization for treating conformational equilibria (multi-gamma state model) provide excellent theoretical models when applied to three polyatomic molecules of increasing conformational freedom.

KeyWords Plus:

FREE-ENERGY CALCULATIONS, RETRO-INVERSO PEPTIDES, THERMODYNAMIC PROPERTIES, CONFORMATIONAL-ANALYSIS, DYNAMICS SIMULATIONS, ALANINE DIPEPTIDE, NONCANONICAL ENSEMBLES, COMPUTER-SIMULATION, GAS-PHASE, WATER

Addresses:

Amadei A, Univ Roma Tor Vergata, Dept Chem Sci & Technol, Via Ric Sci 1, I-00133 Rome, Italy
Univ Roma Tor Vergata, Dept Chem Sci & Technol, I-00133 Rome, Italy
Univ Rome La Sapienza, Dept Chem, I-00185 Rome, Italy