Computational Chemistry

extensive calculations that such HF/3–21G and HF/6–31G energy differences generally give only a rough indication of energy chang ...

reactions spun out of control. One encounters the terms homodesmotic, hyperhomo- desmotic, semihomodesmotic, quasihomodesmotic, ...

A slightly more involved example is the strain of norbornane, bicyclo[2.2.1]heptane. We can open this to heptane (two steps are ...

aromatic ring is opened isodesmically [ 165 ]. This gives consistent results in an incrementally varying series of compounds [ 1 ...

and Liebman [ 169 ]. Schleyer and Puhlhofer discuss various isodesmic schemes and recommend for calculating resonance energies ( ...

This seems unreasonably big: above, we got 89 and 93 kJ mol#^1 for the benzene ASA. Yet the equation seems at first sight reason ...

available as keywords in the Gaussian series of computational chemistry suites [ 177 ], and thecomplete basis set methods, which ...

An MP2(full)/6–31G* geometry optimization, wanted to get a high-quality geometry for all the subsequent calculations (which are ...

(11.0 kcal/mol)” but “these errors are systematic and their effect may be greatly reduced by the use of isodesmic bond additivit ...

available may replace G3(MP2). Within these confines, the question will then be whether to use G3(MP2) or CBS-QB3. Which one, if ...

which the standard state is white phosphorus; although red phosphorus is stabler under normal conditions, these allotropes are a ...

and cheaper than doing a thermochemical experiment, (2) many compounds have not been subjected to experimental determination of ...

wherenis a number large enough to represent thesubstancegraphite rather than just some carbon oligomer. All the species in the f ...

Reference [ 197 ] gives the 0 K G2 value by the atomization method as#195.7 kJ mol#^1 and the experimental value as (from two so ...

¼½ŠðÞ 711 : 2 þ4 216ðÞþ: 035 246 : 8 kJ mol#^1 ##ðÞ 37 : 78430 þ 4 ðÞ## 0 : 50000 74 : 98203 þ#ðފ 115 : 53061 h# 1 : 050 þ 28 ð ...

A calculation using G2 (for comparison with the atomization method, above) gives DHf0-ðCH 3 OHÞ¼ 711 :2kJmol#^1 þDH^0 f0 ¼ 711 : ...

DH-f0ðCH 3 OHÞ¼DH-f0ðCH 4 ÞþDHf0-ðH 2 OÞþDEisodesmic ð 5 : 196 Þ whereDEisodesmic¼DEtotal0KðCH 3 OHþH 2 Þ#DEtotal0KðCH 4 þH 2 OÞ ...

like AM1, discussed inChapter 6). Augmentation with experimental data is still needed for accurate calculations when an ab initi ...

DH-f298ð 1 ; 4 #BQ;CBS#QB3Þ ¼½Š6 711ðÞþ: 2 4 216ðÞþ: 035 2 246ðÞ: 8 kJ mol#^1 #½Šþ# 6 ðÞþ# 37 : 785377 4 ðÞþ# 0 : 499818 2 ðÞ# 7 ...

Considerable attention has been given here to heats (enthalpies) of formation, because there are extensive tabulations of these, ...