On the calculation of atomization energies of organic molecules in the X,a local spin density approximation

 S. FLISZAR, S. RIOUX, AND J. ANDZEL

Abstract

The atomization energies of selected alkanes, alkyl radicals, and amines are deduced from Xa local spin densitycalculations of E, the total energy of a molecule in its potential minimum. Both the exchange-correlation energy, a(aE/au), and aE/au itself obey, in a first approximation, simple atom-by-atom additivity rules. The appropriate a's for use in Xa(LSD) calculations of organic molecules thus appear as weighted averages and depend on the particular composition of each molecule. The at least approximate validity of this averaging procedure is illustrated by the accuracy of calculated atomization energies.

 

 Résumé

 On a dCduit les Cnergies d'atomisation d'une sCrie d'alcanes, de radicaux alkyles et d'amines a partir dcs calculs de E, 1'Cnergie totale d'une molCcule i son minimum de potentiel, basks sur la densit6 locale de spin Xa. L'Cnergie totale de corrtlation-Cchange a(dE/da) et dE/da lui-mCme suivent, en premitre approximation une simple r6gle d'additivitk atome- par-atome. Les valeurs appropriCes de a utilisCes dans les calculs de Xa(LSD) des moltcules organiques sont des moyennes pondCrCes et dtpendent de la composition particulikre de chaque moltcule. La precision des Cnergies d'atomisation calculCes illustre pour le moins la validit6 approximative de cette prockdure. 

 

https://cdnsciencepub.com/doi/pdf/10.1139/v88-489