Ab initio molecular dynamics of protonated dialanine and comparison to infrared multiphoton dissociation experiments

Density functional theory-based Car-Parrinello molecular dynamics is presented at 300 K of the gas-phased ionized Ala-Ala-[H.sup.+] peptide in trans and cis form in accordance with the IR-MPD experimental studies conducted. The experimental IR-MPD spectrum was found to be in excellent agreement in terms of band positions, band shapes and bandwidth.