Oktay Sinanoǧlu

Semiempirical Method for the Determination of Localized Orbitals in Molecules

A semiempirical procedure, based on the minimum‐exchange‐repulsions criterion, but convenient for large molecules, is developed. It is compared with the population‐localization criterion and found preferable. The possibility of the transfer of local orbitals among molecules is discussed. Localization of the sigma subsystems of planar molecules without the pi systems is seen to be justified. The CH2, NH3, H2O, C2H6, C2H4, HCHO, and butadiene molecules are treated as examples.

An intermolecular potential for use in liquids

Abstract An intermolecular potential which takes into account the appreciable effect of a non-polar liquid medium is derived. It depends on macroscopic propertis, and on the local order in the liquid through the relative sizes of “solute” and “solvent” molecules. The CCl 4 - CCl 4 potential in liquid benzene is drawn as an example.

What size cluster is like a surface

Abstract The sizes for which the surface free energy, enthalpy and entropy of a cluster approach those of the bulk planar surface to any desired extent can be obtained from the relations given. Sizes are shown for a non-polar substance, for a polar substance (water), and for bare clusters of metal atoms.

Beam-foil spectroscopy and new atomic structure theory with a survey of results since 1970☆

Abstract BFS has given stimulus to new developments in atomic structure theory and has provided tests of the new approaches. These and previous theoretical approaches to the prediction of allowed and forbidden transition probabilities are critically surveyed. Systematic calculations, based on accurate atomic structure theory including the correlation effects in both ground and excited states, are given for multiplet oscillator strengths for both low and high Zs for nearly all 2s22pn→2s2pn+1 transitions. These compare overall with BFS, Phase-shift, and Hanle experiments within 11%. New results and extension of this theory (NCMET by Sinanoǧlu) to M-shells (Mg, Al, Si, S, Cl,...) by Sinanoǧlu and Beck are compared with recent BFS experiments and examined. Predicted lifetimes suggesting BFS experiments on highly-stripped heavy ions in accelerators like SUPER-HILAC and tandems are given. Recent developments in theory and experiment on multiply-excited spectra are outlined. Lifetimes of metastable states in [C I], [O I], [O II], [N II], etc. are also presented.

A theorem for qualitative deductions in organic or inorganic chemistry regarding the relative stabilities, distortions and reactions of molecules

Abstract Regardless of symmetry, the qualitative behavior of molecules, individually or in classes, may be predicted vis-a-vis their relative stabilities, defor

New theoretical transition probabilities for the Si I 3s23p23pP — 3s3p33D0 isoelectronic sequence including the important correlation effects

Abstract We report results for P II, Cl IV (interpolated), Ca VII, Fe XIII 3P-3D0f-values, which are in good agreement with experiment and are obtained from the news atomic structure theory of Sinanoǧlu including electron correlation.

Locally attractive normal modes for chemical process

It is shown that if along a normal mode of perturbation of a steady state which is far from equilibrium, the mixed second variation of the entropy is a constant of motion, this mode is locally attractive and the system becomes structurally unstable (in the sense of Adronov and Pontriaguin). In general, the existence of such a mode indicates chemical oscillation. In the special case that the mode has also a vanishing imaginary part of the frequency, it leads to the formation of a dissipative spatial structure.

Electronic quadrupole moments of excited states and the charge wavefunction of the many-electron theory

Abstract It is shown that the electronic quadrupole moment as a measure of the charge distribution in non-closed shell systems is given not by the Hartree-Fock wavefunction, ΦRHF, but by the “charge distribution wavefunction” (the “charge wavefunction”) of NCMET, ϑc. The electronic quadrupole moments, Θ, of Be 1 1s22s2p3p0, B I 1s22s22p 2p0, B I 1s22s2p24P, B I 1s22s2p22D, and CI 1s22p32D0 are calculated by the full charge wavefunctions of NCMET and the Hartree-Fock wavefunctions. In C II, RHF gives Θ = 0.0 while the NCMET values are Θ = 0.07726 for J = 5 2 and Θ = 0.05408 for J = 3 2 . Where several l ≠ 0 orbitals are involved in the excited state, the RHF results can differ sizably from the accurate NCMET charge wavefunction results. Recent beam measurements of electronic quadrupole moments are pertinent to these conclusions.

Reducible and irreducible pair correlations in benzene

Abstract Molecular orbital pair correlation energies in benzene are evaluated by two methods within a framework limited to a finite 2pπ-basis. Both the MO-pairs (“reducible”) and irreducible symmetry pair correlations are obtained.

Global attractors and global stability for closed chemical systems

The structural stability in the sense of Adronov and Pontriaguin for kinetic models of a closed reacting mixture is investigated. Necessary and sufficient conditions for the mass‐action kinetics model to be structurally stable are derived.