Abstract: Based on the Becke method and the Hirshfeld method, we calculated the atomic contribution of the valine molecular orbits. 
The  results show that the qualitative results of the analysis of high occupied orbit by the Becke method and the Hirshfeld method are basically consistent,  and the quantitative results are  slightly different.  The qualitative results of analysis of virtual orbit are  not completely consistent, and the quantitative results are obviously different.

Key words: valine, orbital component, atomic orbit, contribution