The eigen modes of the flux line lattice (FLL) are discussed under a suitable transformation of the field operators. The non-local effective Hamiltonian governing the fluctuation of the FLL can be diagonalized. The melting of the Abrikasov flux lattice has also been studied by using the Lindemann criterion. We found that in order to meet the requirement of the melting criterion, the flux line lattice has to be softened significantly at low temperature, more than at high temperature. This general feature agrees with the experimental results satisfactorily. In the high temperature limit, our results reduce to those obtained by A. Houghton.
Chinese Journal of Physics=中國物理學刊 31(6-II)，頁1019-1024