tral alanine in the gas phase is summarized in Table , where we report in the right column the average frequencies of the effective modes. As done previously in Table II, we compare our analysis to the results of Ref. , whose frequencies are listed in the left column. The central columns report the bands assignment, using again the notation introduced in Ref. . With respect to the zwitterionic form of alanine, the agreement between our effective mode analysis and the experimental spectrum of Ref. for the neutral form turns our to be even slightly better.