Gas phase structural stability of neutral and zwitterionic forms of alanine in presence of (H2O)n=1-7 clusters: A density functional theory study

► The gas phase stability of Ala and ZAla has been investigated in the presence of water clusters. ► Ala-(H2O)3 and ZAla-(H2O)3 were found to have same structural energy. ► For n ⩾ 4, the ZAla-(H2O)n is more stable over Ala-(H2O)n complex. ► The frequency of hydrogen bond bridging mode has also been calculated. ► The frequency of ν(CO) and ν(CO) shifted towards red by increasing the cluster size.