HEAT High-accuracy Extrapolate Ab initio

HEAT (High-accuracy Extrapolate Ab initio Thermochemistry), 3,160 Hellmarm-Feynman theorem, 1, 21 HF limit, 3,197... 

The HEAT (high accuracy extrapolated ab initio thermochemistry) method, which has no empirical parameters, uses CC calculations up to CCSDTQ, extrapolations to the CBS limit, corrections for vibrational anharmonicity, relativistic effects, and deviations from the Bom-Oppenheimer approximation to achieve mean absolute deviation of 0.1 kcal/ mol in atomization energies. The high level of calculations means the method can be used only with tetraatomic or smaller molecules. HEAT, like the other methods in this section, exists in several versions [A. Tajti et al., J. Chem. Phys., 121, 11599 (2004) J. Y. Bomble et al., ibid., 125, 064108 (2006)]. 

There are several other composite approaches, for example, complete basis set (CBS) models [56], focal-point analysis [57], multi-coefficient correlation methods [58], high-accuracy extrapolated ab initio thermo-chemistry (HEAT) [59] and the Weizmann-4 theory [60]. Hansen et al. [61] have employed the so-caUed MP2 DFT [193] scheme for analysing benzene ethylation over H-ZSM-5. Density functional calculations applying periodic boundary conditions [Perdew-Burke-Emzerhof (PBE) functional] were combined with MP2 energy calculations on a series of... 

On the other hand, computational thermochemistry values in the sub-kUojoule per mole accuracy range are now possible only for small molecules. They can be calculated through the highly accurate extrapolated ab initio thermochemistry (HEAT) [53] approach developed by an international group of researchers and by the Weizmann-4 (W4) method [54] from Martin s group, which was benchmarked on atomization energies of 99 small molecules [55]. They further developed an... 

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