Abstract: Using the B3LYP method of density functional theory, we optimized the geometric configuration of Ala molecules under implicit solvent, under the same theoretical method, we calculated the orbital wave function and charge decomposition analysis (CDA) of the Ala system fragments under the implicit water and methanol solvent. The results show that the calculated results of the extended charge decomposition analysis (ECDA) of CH₃ fragements are 0.001 3, and the results of the ECDA calculation of the NH₂ fragements are 0.000 8 under implicit methanol solvent and implicit water solvent, 
the quantitative results are basically consistent. Comparison of r_i of the CDA calculation results of CH₃ and NH₂ fragments, the qualitative results are basically consistent.

Key words: alanine, implicit solvent, charge decomposition, wave , function