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Bucinsky L.,Institute of Physical Chemistry and Chemical Physics | Malcek M.,Institute of Physical Chemistry and Chemical Physics | Biskupic S.,Institute of Physical Chemistry and Chemical Physics
International Journal of Quantum Chemistry | Year: 2016

Many fermions Kramers pairs formalism is considered from the prospective of the sum of individual single fermion time-reversal operators. The obtained many fermions "pseudo Kramers pairs operator" ( K'), as well as its square ( K'2), have formally the same structure as the many fermion spin operators Ŝ and Ŝ2. Nevertheless, the shape of K'2 eigenfunctions with respect to Ŝ2 and Ŝz is different. Herein all Kramers adapted eigenfunctions of K'2 for cases of up to four unpaired fermions are compiled, and their properties with respect to K' further advocated. It will be shown that degeneracy of the K'2 multiplets recovers the proper behavior with respect to Pascal's triangle. A projection operator for obtaining the "high spin" Kramers adapted eigenfunctions is suggested. Noncommutation of K'2 with spin and angular momentum operators and degeneracy is discussed at last. © 2016 Wiley Periodicals, Inc. Source


Sladek V.,Institute of Physical Chemistry and Chemical Physics | Bucinsky L.,Institute of Physical Chemistry and Chemical Physics | Matuska J.,Institute of Physical Chemistry and Chemical Physics | Ilcin M.,Institute of Physical Chemistry and Chemical Physics | And 2 more authors.
Physical Chemistry Chemical Physics | Year: 2014

CCSD(T) ground state potential curves of Pb⋯RG systems (RG = He, Ne and Ar) are presented and the importance of the inclusion of spin-orbit effects is discussed. The closed-shell character of the Pb atom at the two-component relativistic level of relativistic theory leads to shallower potential energy curves compared to scalar relativistic open-shell calculations. The pressure-independent cross-diffusion coefficients pD12 have been simulated using the extrapolated two-component CCSD(T) ground state potential curves. The diffusion coefficients from scattering theory are compared with simulations based on molecular dynamics (MD) using the velocity autocorrelation function (VACF) and the Einstein equation. A correction for the proper assessment of the uncertainty in the VACF is proposed. The acceleration of the MD simulation of Pb in RG diffusion is proposed utilizing the RG in Pb diffusion. The dU[TQ]Z/CCSD(T) potential curve of Pb⋯He (De = 8.667 cm-1, re = 4.683 Å) supports only one vibrational level. The anharmonicity of this potential is compared to the potential of He⋯He which also supports only one vibrational level. The comparison is based on the mean square separations of the vibrational wave function. © the Partner Organisations 2014. Source

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