Mean-field theory of elastic dipoles on a face-centered-cubic lattice

AbstractThe T – P phase diagrams of the halogenomethane compounds (CCl_4 – _ n Br_ n , n = 0, 1, 2, 4) are calculated using a mean field model. By expanding the free energy in terms of the order parameters for the transitions of the liquid (L), rhombohedral (R), face-centered cubic (FCC) and monoclinic (M) phases in those compounds, the phase line equations are derived and they are fitted to the experimental data from the literature. This method of calculating the T – P phase diagram is satisfactory to explain the T – P measurements for the halogenomethane compounds and it can also be applied to two-component systems.

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Nature of Non-magnetic Strongly-Correlated State in Plutonium

MRS Proceedings ◽

10.1557/proc-986-0986-oo01-07 ◽

2006 ◽

Vol 986 ◽

Author(s):

Leniod Purovskii ◽

Alexander Shick ◽

Ladislav Havela ◽

Mikhail Katsnelson ◽

Alexander Lichtenstein

Keyword(s):

Field Theory ◽

Density Functional ◽

Local Density ◽

Mean Field Theory ◽

Mean Field ◽

Dynamical Mean Field Theory ◽

Cubic Phase ◽

Face Centered Cubic ◽

Strongly Correlated ◽

Starting Point

AbstractLocal density approximation for the electronic structure calculations has been highly successful for non-correlated systems. The LDA scheme quite often failed for strongly correlated materials containing transition metals and rare-earth elements with complicated charge, spin and orbital ordering. Dynamical mean field theory in combination with the first-principle scheme (LDA+DMFT) can be a starting point to go beyond static density functional approximation and include effects of charge, spin and orbital fluctuations. Ab-initio relativistic dynamical mean-field theory is applied to resolve the long-standing controversy between theory and experiment in the “simple” face-centered cubic phase of plutonium called δ-Pu. In agreement with experiment, neither static nor dynamical magnetic moments are predicted. In addition, the quasiparticle density of states reproduces not only the peak close to the Fermi level, which explains the large coefficient of electronic specific heat, but also main 5f features observed in photoelectron spectroscopy.

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Reentrance Phenomenon of a Mixed Spin Ising Model

International Letters of Chemistry Physics and Astronomy ◽

10.18052/www.scipress.com/ilcpa.56.31 ◽

2015 ◽

Vol 56 ◽

pp. 31-36

Author(s):

Hadey K. Mohamad

Keyword(s):

Field Theory ◽

Phase Transition ◽

Magnetic Phase ◽

Mean Field Theory ◽

Mean Field ◽

Lattice Disorder ◽

Cubic Lattice ◽

Mixed Spin ◽

Simple Cubic ◽

Simple Cubic Lattice

A reentrant magnetic phase transition in molecular based magnet AFeIIFeIII(C2O4)3[A=N(n-CnH2n+1)4, n=3-5] is investigated by the use of Mean-Field Theory (MFT) for a mixed spin-2 and spin-5/2 Ising system on a simple cubic lattice. It is found that a double-entrant ferrimagnetic behaviour in the mixed-spin system depends on the negative values of the anisotropies in the order-disorder system for the two sublattices of the mixture. It is shown using numerical calculations that this phenomenon is strongly affected by the magnetic anisotropy and lattice disorder.

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