H. Nagao et al., THE HUCKEL MODEL BY MEANS OF THE PATH-INTEGRAL METHOD .2. APPLICATIONTO THE SQUARE LATTICE SYSTEM, Chemical physics letters, 215(1-3), 1993, pp. 5-10
The path integral method is applied to the Huckel model for the square
lattice. We evaluated the general transition amplitude of the infinit
e square lattice. The explicit expression of the transition amplitude
for the finite square lattice system is also derived by introducing th
e appropriate virtual sources to the infinite system.