Raport of the scientific activity

 

 

During my three monthly visit in the Bogoliubov Laboratory for the Theoretrical Physics of the Joint Institute for Nuclear Research – Dubna (Russia), my work can be described as following:

 

1. First month was devoted to the problem of the derivation of the effective hamiltonian to describe strongly correlated electron systems with the orbital degeneracy. Especially, it was connected with the α΄ - phase of the sodium vanadate α΄ - Na V₂ O₅ and the sodium pyroxene Na Ti Si₂ O₆ ladder compounds.

 

2. Second month was devoted to the calculation of the dynamical spin susceptibility in a paramagnetic phase for the t-J model in terms of the Hubbard operators. An equation of motion method was applied for the relaxation function, which is presented in terms of the memory function. Further intentions is to perform similar calculations for the t-J model with vacancy site.

 

3.   Third month was devoted to the calculations of the static susceptibilities for

       the zero- ( χ ₀ ) and for the antiferromagnetic wave vectors ( χ _Q ) for the t-J  

       model in terms of the Hubbard operators. It was used projection techniques in 

       the equation of motion for the Zubarev’s thermal Green function. After

       performing the corresponding numerical calculations, this work is planed to be

       prepared for publication firstly of all.