Quantum chemistry, theory

P. Politzer, J. S. Murray, In Recent Research Developments in Biological Applications of Quantum Chemistry Theory, C. Kubli-Garfias (ed.), Research Signpost, Trivandrum, India, 2002, in press. 

Hameka, H. F. Advanced quantum chemistry. Theory of interactions between molecules and electromagnetic fields. Reading, Mass. Addison-Wesley Publishing Company, Inc. 

Concentrates on the math behind quantum chemistry theory and algorithms, yet not dryly written. Best read after acquiring the basics from a more general, introductory book. 

Per-Olov Lowdin and Yngve Ohrn, Quantum Chemistry, Theory of Condensed Matter, and Propagator Methods in the Quantum Theory of Matter. Proceedings of the International Symposium held at Flagler Beach, Florida, March 1-3 and 7-13,1982, in Int. J. Quantum Chem., Quantum Chem. Symp., No. 16, Wiley, New York, 1982. Per-Olov Lowdin and Michael C. Zerner, Quantum Biology and Quantum Pharmacology. Proceedings of the International Symposium held at Palm Coast, Florida, March 14-16,1983, in Int.J. Quantum Chem., Quantum Biol. Symp., No. 10, Wiley, New York, 1983. 

In this part, we will not give an overview of the quantum chemistry theory that has led to the current state of affairs, as excellent introductions can be found elsewhere. We will rather shortly describe which methodology can be followed to describe acid zeolite catalyzed reactions. 

Besides aetive research he very much enjoys teaching. In the Physical-Teehnieal Institute of Moseow he taught (1966-1992) general courses on Molecular Dynamics and Chemical Kinetics. In the Teehnion (since 1992) he has taught and still teaehes graduate eourses on different subjeets Advanced Quantum Chemistry, Theory of Moleeular Collisions, Kinetie Proeesses in Gases and Plasma, Theory of Fluetuations, Density Matrix Formalisms in Chemical Physics etc. 

Once the concept of molecular structure vas definitively consolidated by the successes of quantum-chemistry theories and the approaches to the calculation of numerical indices encoding molecular structure information vere accepted, all the constitutive elements for the take-off of QSAR strategies vere available. 

The Symposium Quantum Chemistry - Theory, Models, and Computations is organized to celebrate Professor Osvaldo Goscinski s 65th birthday. Professor Osvaldo Goscinski will be 65 years on October 29 and retires from his chair as Professor of Quantum Chemistry on November 29... 

H.F. Hameka, Advanced Quantum Chemistry. Theory of Interactions Between Molecules and Electromagnetic Field, Addison-Wesley, Reading, MA (1965). 

In the field of quantum chemistry, theories on electronic motion states commencing with the Hartree-Fock method have intended to incorporate electron correlation more efficiently. However, due to the long computational times required, quantum chemistry calculations had been mostly restricted to trial applications by theoreticians until the 1980s. In the 1990s, density functional theory (DFT) appeared in quantum chemistry to resolve this situation. After this, DFT has become widespread, so that is now the main theory, which is used in more than 80% of quantum chemistry papers in 2014. 

The nature is always relativistic. Non-relativistic objects do not exists. The only way to see the role of relativistic effects in chemistry is through the comparison between relativistic and nonrelativistic theory and results. The values of the relativistic effects for a given quantity X are then usually calculated as a difference between the relativistic and nonrelativistic values of this quantity, i.e. AX = X rel) — X nrel) calculated at the same level of theory. Therefore, from both fundamental and practical points of view there is a necessity for relativistic quantum chemistry theory and applications. While the Hamiltonian of a molecule is exactly known in nonrelativistic quantum mechanics, this is no longer the case for the relativistic formulation. Many relativistic Hamiltonians have been derived over the past decades. It goes beyond the goal of this chapter to review all of the... 

The improvements within the hierarchy of A -electron models is probably a more complicated task. There are a couple of quantum-chemistry theories that allow us to approach the exact Schrodinger equation systematically. Among them the coupled-cluster (CC) method represents probably the most successful approach. It can be applied to relatively large systems and the theory is both size-extensive and size-consistent. So far the only way to approach the exact Schrodinger equation, within the hierarchy of the A -electron models (following the horizontal axis on Figure 1), is the systematic extension of the excitation level. In CC theory there is a series of models that refer to the way the cluster operator is truncated (CCS, CCSD, CCSDT, CCSDTQ and so on). In the limit of the untruncated cluster operator the CC wave function becomes equivalent with full Cl, which is the exact solution of the Schrodinger equation within a particular basis set. The truncation level indicates, in some sense, the accuracy of the model which is almost always limited by the available computational resources. 

In principle, the microscale kinetics can also be obtained directly by quantum chemistry theory, TST or VTST theory, which, to a large extend, reflects the intrinsic kinetics for elementary reaction steps in MTO process. But so far, most of the theoretical calculations had only concentrated on part of the elementary reactions steps (Hemelsoet et al., 2011 Lesthaeghe et al., 2009 Van Speybroeck et al., 2011 Wang et al., 2010 Xu et al., 2013). 

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