1. A method for evaluating similarity deviation between molecular orbitals, comprising: a) selecting two molecular orbitals to be compared for molecular orbital similarity, and obtaining N x MBS pairs by i) computing molecular orbital distributions by a quantum chemistry calculation, ii) building N blocks arranged in a radial direction from the center of the molecular structure, iii) calculating a molecular orbital ratio (BX(k)) associated with each of the blocks (k is a natural number and represents a block number ranging from 1 to N), iv) rearranging the blocks consecutively by orbital ratio (BX(k)) size, v) with the exception that blocks are built at different sizes, repeating steps ii) to iv) for the individual molecular orbitals of interest to give N x MBS (multi-block spectra) per molecular orbital, the MBS being different in block size, and assembling N x MBS pairs by block size; b) performing multi-step identity estimation on the N x MBS pairs to calculate TSS(m) for each of the MBS pairs (m is an MBS number ranging from 1 to N x ); and c) calculating a standard deviation of TSS (m) for each of the MBS pairs, and evaluating similarity deviation between molecular orbitals on the basis of the calculated deviations.