Sivaramakrishnan R, Tranter Robert S, Brezinsky K
Department of Chemical and Mechanical Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, USA.
J Phys Chem A. 2005 Mar 3;109(8):1621-8. doi: 10.1021/jp045076m.
Density functional theory (DFT) has been used along with isodesmic reaction schemes to estimate heats of formation for aromatics and polynuclear aromatic hydrocarbons (PAHs). Calculations have been performed for 42 molecules, 12 of which have uncertain or unknown experimental values, using the B3-LYP functional with the small 6-31G(d) basis set. Heats of formation for the group of test molecules were estimated using both conventional bond separation (BS) isodesmic reactions as well as a new technique of ring conserved (RC) isodesmic reactions which is able to correct systematic errors in B3-LYP calculations. When a ring conserved isodesmic reaction based on delocalization energies is used, the estimated heat of formation is more accurate than that obtained by the bond separation technique. The methodology for creating and using appropriate ring conserved isodesmic reactions is discussed. The present scheme also compares favorably against a recently developed bond centered group additivity scheme that was tested against a large number of PAH molecules.
密度泛函理论（DFT）已与等键反应方案一起用于估算芳烃和多环芳烃（PAHs）的生成热。使用B3-LYP泛函和小基组6-31G(d)对42个分子进行了计算，其中12个分子的实验值不确定或未知。使用传统的键分离（BS）等键反应以及一种新的环守恒（RC）等键反应技术来估算测试分子组的生成热，该技术能够校正B3-LYP计算中的系统误差。当使用基于离域能的环守恒等键反应时，估算的生成热比通过键分离技术获得的更准确。讨论了创建和使用适当的环守恒等键反应的方法。本方案与最近开发的针对大量PAH分子进行测试的键中心基团加和方案相比也具有优势。
