Partition function of the two-dimensional nearest neighbour Ising models for finite lattices in a non-zero magnetic field

The partition function for two-dimensional nearest neighbour Ising model in a non-zero magnetic field have been derived for a finite square lattice of 16, 25, 36 and 64 sites with the help of graph theoretical procedures, show-bit algorithm, enumeration of configurations and transfer matrix methods. © Indian Academy of Sciences.