Title: Phase diagrams of the Bose-Hubbard model at finite temperature
Author(s):

	I.V. Stasyuk (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79021 Lviv, Ukraine) ,
	T.S. Mysakovych (Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine, 1 Svientsitskii Str., 79021 Lviv, Ukraine)

The phase transitions in the Bose-Hubbard model are investigated. A single-particle Green's function is calculated in the random phase approximation and the formalism of the Hubbard operators is used. The regions of existence of the superfluid and Mott insulator phases are established and the (μ,t) (the chemical potential - transfer parameter) phase diagrams are built. The effect of temperature change on this transition is analyzed and the phase diagram in the (T,μ) plane is constructed. The role of thermal activation of the ion hopping is investigated by taking into account the temperature dependence of the transfer parameter. The reconstruction of the Mott-insulator lobes due to this effect is analyzed.

Key words: Bose-Hubbard model, phase transition
PACS: 03.75.Lm, 05.30.Jp

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