And ab initio computations

Carved wooden bears in all shapes and sizes overwhelmed Yngve and me at our visit to Noboribetsu in 1976. There was an afternoon to spare before the opening of the "Oji International Seminar on Theories and Ab Initio Computations of Molecular Electronic Structure" at Tomakomai, Hokkaido in the fall of 1976 so we wished to experience the hot springs. The train left us with a choice of buses, the desdnations of which were clearly indicated in Japanese writing. We found the right one and came to a city in a canyon where the sulfur fumes and hot water let themselves out. The kind reception by Kimio Ohno and Fukashi Sasaki at Hokkaido University remains a vivid memory. 

The above qualitative conclusion obtained by the CNDO/BW method was also confirmed by MINDO/3 and ab initio computations. The latter were carried out using both minimal STO-3G (129) and extended STO-3G, 3-21G, and 3-21G basis sets (16). The simplest cluster of type (a) was considered with hydrogens as terminal atoms. As in the semiempirical case, the ab initio calculations predicted certain, although less in absolute value, shifts of A1 atom is along the z-axis. This shift decreased with extension of the basis set. However, the introduction of polarization functions (id AO of Al) in a basis somewhat increased the effect. 

Oxide nanopartides, unlike nanopartides of metals, display an expansion in their lattice parameters in comparison with the bulk. Tsunekawa et al. have examined sub-10 nm Ce02 and sub-100 nm BaTi03 nanopartides using a combination of electron diffraction, X-ray photoelectron spectroscopy and ab initio computer simulations. They find that in the Ce02 system, the lattice expansion arises from a decrease in Ce valence, whilst in the BaTi03 system, the decreasing Ti-0 covalency with decreasing particle size results in the expanded lattice. 

Unified theory and ab initio computation of the wavefunctions and spectra just below and just above the fragmentation threshold, with application to atoms... 

The questions that we are really asking concern the very nature of quantum chemistry, what relation it has to experiment, what function we expect it to fulfill, what kind of questions we would like it to answer. 1 believe we are divided in our own answers to these questions" (Coulson 1960, 172). Coulson believed that the problems culminating in the then-present deadlock could be traced to the recommendations made at the 1955 Molecular Quantum Mechanics Conference, organized at the University of Texas (see the previous section "Computers and Ab Initio Computations"). He was uncharacteristically persistent "It is in no small measure due to the success of these programs that quantum chemistry is in its present predicament" (Coulson 1960, 172). 

Trifluoromethylnitromethylcarbene anion has been proposed as a reactive inter-mediate and the reactivity of diethenylnaphthalenes towards anionic polymerization has been predicted by semiempirical and ab initio computation. ... 

Klapotke, T.M., Schulz, A., McNamara, J. Preparation, characterization and ab initio computation of the first binary antimony azide, Sb(N3)3. J. Chem. Soc. Dalton Trans. 2985-2987 (1996)... 

Figure 8 Variable-time NR+ spectra of (CH3)2SH+ formed by chemical ionization of (CH3)2S with (CH3)2CH=OH+. Dimethyl disulfide and oxygen served as the neutralization and reionization targets, respectively. The observation times of the neutrals are 0.35 j.s (left), 1.05 j.s (centre), and 1.76 xs (right). The corresponding observation times of the ions are 3.44 o,s (left), 2.73 xs (centre), and 2.02. is (right). Reprinted with permission of Elsevier from Sadilek M and Turecek F (1999) Metastable states of dimethylsulfonium radical, (CH3)2SH a neutralization-reioniza-tion mass spectrometric and ab initio computational study. Inter-nationalJournal of Mass Spectrometry 639-649.

Ferre-Vilaplana, A. (2005) Numerical treatment discussion and ab initio computational reinvestigation of physisorption of molecular hydrogen on graphene. J. Chem. Phys., 122, 104709. 

O Connor, J.M., Baldridge, K.K., Rodgers, B.L., et al. (2010) A photochemical metallocene route to anionic enediynes synthesis, solid-state structures, and ab initio computations on cyclopentadienidoenediynes. Journal of the American Chemical Society, 132(32), 11030-11032. 

Foces-Foces, C., Echevarria, A., Jagerovic, N., Alkorta, L, Elguero, J., Langer, U., Klein, O., Minguet-Bonvehi, M. Limbach, H-. (2001) A Solid-State NMR, X-ray Diffraction, and ab Initio Computational Study of Hydrogen-Bond Structure and Dynamics of Pyrazole-4-Carboxylic Add Chains, J. Am. Chem. Soc. Vol. 123 7898-7906. 

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