An efficient implementation of local excitation approximation(LEA)approach is presented for predicting the blueshift of the local n→π* electronic vertical excitation in condensed phase at ab initio level.We propose a new localizing procedure to obtain regional local molecular orbitals(RLMO)using singular value decomposition(SVD)algorithm.[1] The main idea of the LEA scheme is that the only local electron excitations within selected reference subspace are treated to calculate the target excited state wavefunctions.This concept is realized by using the localized molecular orbitals(LMO)localized on the chromophore substructure.For the target transitions which show the strong local character within the chromophore region,the LEA scheme can provide excited state properties without much loss of accuracy.Using this LEA scheme and molecular dynamics simulation,we study the solvent effect on the local n→π* excitation energy in formaldehyde and acetone in aqueous solution.Statistical analyses using 600 configurations generated from molecular dynamics simulation are presented for acetone and formaldehyde,respectively.The blueshift in the n→π* vertical electronic excitation energy was 1453±52 cm-1 for acetone and 1490±53 cm-1 for formaldehyde.The results are in good agreement with the available experimental blue shift of 1500±200 cm-1.