Nanocomposites and nanomaterials

Configurational model of quasi-2D organic conductor electron subsystem
Skorenkyy Yu.
Ternopil Ivan Puluj National Technical University, 56 Ruska St, Ternopil, Ukraine. 
E-mail: skorenkyy@tntu.edu.ua

Now it is commonly agreed that the organic systems of (BEDT-TTF)2X, (BETS)2Y families, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene molecule and BETS is bis(ethylenedithio)tetraselenafulvalene, X denotes monovalent anion (X = Cu[N(CN)2]Cl, Cu[N(CN)2]Br, Cu[N(CN)2]I, Cu(SCN)2, ICl2, AuBr2, AuI2, Ibr2, I3) are strongly correlated organic conductors the electron subsystem of which can be described within Hubbard-type model with strong intra-site repulsion [1]. However, qualitative difference of the behavior under the external actions for compounds of different band filling as well as absence of the electron-hole symmetry of the extended phase diagram, describing the effect of hydrostatic and chemical pressure, requires the model generalization by taking into account the correlated hopping of electrons [2]. Such a model has been developed recently for investigation of the conditions for pseudogap opening in the spectrum and anomalies in dispersion of current carriers of quasi-1D organic conductors [3]. 
We derive an effective Hamiltonian of a model with correlated hopping of electrons to study the inﬂuence of the external pressure, temperature and doping on a phase transitions in quasi-2D organic conductor by means of canonical transformation. The single electron Green function and quasiparticle energy spectrum of the model have been calculated using a variant of generalized Hartree-Fock approximation. This procedure has allowed us to obtain analytical expression for the band narrowing factor and relatively simple and transparent equations for calculation of the band gap and eﬀective masses of the current carriers. 

1.	Scriven E., Powell B.J. Toward the parametrization of the Hubbard model for salts of bis(ethylenedithio)tetrathiafulvalene // J. Chem. Phys.-2009.-130.-104508.
2.	Skorenkyy Yu. et al. Mott transition, ferromagnetism and conductivity in the generalized Hubbard model // Acta Physica Polonica A.- 2007.-111.-P.635-644.
3.	Skorenkyy Yu., Kramar O. Antiferromagnetic ordering and pseudogap in a model of quasi-1D organic superconductor electronic subsystem // Mol. Cryst. Liq. Cryst.- 2016.- 639.-P.24-32.