Ab initio studies on the structures of the hydrogen-bond clusters C5H10NH(NH3)n-(n-=1-3)

The equilibrium geometrical structures of hydrogen-bond clusters C5H10NH(NH3)(n)(n=1-3) were studied by ab initio MO theory with RHF/6-31G(d) basis set level. The calculated results show that the most stable structures of C5H10NH (NH3)(n) are one linear hydrogen-bonding, three-cyclic and four-cyclic structures for n=1, 2, 3, respectively. At MP2/6-31G(d)//B3LYP/6-31G(d) level, the MO population analysis of the most stable configurations C5H10NH(NH3)(n)(I) (n=1-3) has been employed, and the corresponding occupied molecular orbitals have been assigned. Their calculated vertical ionization potentials (P-VI) show that the formation of hydrogen bonds causes the P-VI values to decrease.