A simple model of photofield emission calculation is discussed. A spatially dependent vector potential is used to evaluate the matrix element for calculating the photofield emission current density. We have presented a model in which Projection Operator method of group theory has been applied to deduce initial state wave function Ψi for a particular surface state pertaining to a particular point group. The model will also take into account the bulk and the surface state bands of different symmetry and also considers the effect of variation of vector potential. We have considered the point Δ2' for which the point group is C4v which corresponds to the surface states. By introducing the atomic orbital Φ (z), the final form of initial state wavefunction is calculated.