Several stories from theoretical chemistry with some Russian flavor and implications for theorems of chemistry, vagueness of its concepts, fuzziness of its definitions, iconicity of its language, and peculiarities of its nomenclature

Abstract

We present an informal discussion of the problems related to emergence and development of theoretical chemistry concepts and their relation to those of quantum mechanics and general mathematical thinking. This also brings us to a discussion of axiomatization of chemical knowledge, relation between iconic language of (organic) chemistry and symbolic language of physics, relations between molecular orbital and valence bond pictures of molecular electronic structure and other similar problems. Because of the thematic orientation of the present issue of the Int. J. Quantum Chem. Russian contributions to setting and solving the above problems are highlighted.

Magnetic Properties of Quasi-One-Dimensional Crystals Formed by Graphene Nanoclusters and Embedded Atoms of the Transition Metals

“…Note also, besides the numerous successful applications in solid-state physics, Heisenberg spin Hamiltonian is also treated as the spin formalism of known valence bond methods of quantum chemistry [27][28][29]. Unfortunately, this approach is not programmed in the existing solid-state quantum chemistry packages.…”

Quantum Mechanical/Molecular Mechanical (QM/MM) Approaches

“…To perform such a strong electron localisation, one should remove the orthonormal constraint on the wave functions, which necessitates the switch from canonical Hartree-Fock (and correspondingly Kohn-Sham in DFT) equations and their orbital solutions to noncanonical orbitals, subject to Adams-Gilbert equations (Danyliv and Kantorovich, 2004;Danyliv et al, 2007). Much effort has, therefore, concentrated on the derivation of appropriate embedding schemes (Abarenkov et al, 2011;Abarenkov and Tupitsyn, 2001;Antes and Thiel, 1999;Danyliv and Kantorovich, 2004;Danyliv et al, 2007;Guo et al, 2012;He et al, 2009;Hégely et al, 2016;Huzinaga et al, 1987;Kantorovich, 1983Kantorovich, , 1988Laino et al, 2006;Manby et al, 2012;Milov et al, 2015;Seijo and Barandiarán, 1996;Shidlovskaya, 2002;Tchougréeff, 1999Tchougréeff, , 2016Wesolowski et al, 2015). In this respect, the external potential can originate from the surroundings, represented by their charge density, giving rise to the family of so-called Density-Functional…”