Model Description of the H-Bonded Transuranium Complexes

Abstract

In the framework of configurational model it is established that regions of existence of various forms of actinide hydroxocomplexes at variation of solution pH depend on differences of configuration energies and temperature. Saturation effect is found out, which leads to a sharp change of ligand concentration. Model of the polymerization of ionic groups UO 2 [(OH) 2 UO 2 ] 2+ n into chain structure via hydrogen bonds is proposed. The thermodynamic stability of such a formation is investigated depending on the number of links at different temperatures and at various boundary conditions.

Coherent Tunnel Repolarization of a Hydrogen Bonded Chain

“…taking into account only two lowest proton levels, one may introduce Fermi-operators a + r,k (a r,k ) and a + l,k (a l,k ) of proton creation and annihilation in the right and left wells of a k-th hydrogen bond. As shown in [8], orientation transitions of A-H groups can be described in terms of a proton subsystem as a pseudo-tunnel effect. The Hamiltonian of this model can be written as [8]:…”

“…As shown in [8], orientation transitions of A-H groups can be described in terms of a proton subsystem as a pseudo-tunnel effect. The Hamiltonian of this model can be written as [8]:…”

“…corresponds to the Coulomb repulsion energy between two protons in the same hydrogen bond and that of free electron pairs, with protons missing [8,9,30]. For simplicity, we regard that all hydrogen bonds are equivalent and the chain obeys the periodical boundary condition.…”

“…The latter becomes possible when protons are tightly bound with the ion groups, so that the probability of proton transfer processes along the hydrogen bond is lower than that of orientation effects of the group O-H. To illustrate the feasibility of such transitions it is sufficient to study the simplest models of orientation oscillations of the ionic groups of a hydrogen bonded chain [7,8,20,21]. In the two-level approximation, these models can be reduced to the model of an easy-axes ferromagnetic with a transverse external field for which the effect of a macroscopic quantum coherence was considered in detail (see, e.g., [16][17][18][19][20]).…”

“…If we neglect the excited states and consider a 2-level scheme, then, in a pseudo-spin representation, the secondary quantised Hamiltonian of such a system is known to be reduced to the model of easy-axes ferromagnetic with a transverse external field [5]. To estimate the frequency of coherent orientation tunnel transitions we consider another model [8] that takes into account both the proton dynamics of hydrogen bonds and the reorientation processes of O-H groups. This model admits two limiting cases of particular interest for the study.…”