Thermodynamic functions of an electron gas in strongly anisotropic crystals for different models of electron spectrum

Different models of electron energy for GaSe are considered for the purpose of deriving thermodynamic functions for an electron gas at low and high temperatures. Their common features and differences are pointed out and their agreement with existing data is analyzed. The results show cases where the two models are equivalent. We also show conditions at which they yield different results and therefore peculiarities of the chemical bonding are to be taken into consideration.