Physical Review
Theory of Nonlinear Effects in Crystals in the Second-Quantization Representation
Dragutin Lalović, Bratislav S. Tosic, R. B. Žakula
Abstract
A method for an exact theoretical treatment of nonlinear (anharmonic) effects in crystals in the second quantization representation is presented. The method represents essentially a generalization of Bogolyubov's method of approximate second quantization. In addition, the Fermi representation of elementary excitation creation and annihilation operators is given.