Nonempirical calculations of potential energy surfaces of intramolecular rearrangements in LiMH2 systems (M=B, Al, C+, Si+)

Within the SCF/3-21G approximation different cross sections of potential surfaces (PS) of intramolecular rearrangements in LiBH2, LiAlH2 molecules and LiCH2, LiSiH2+ ions in lower singlet states are calculated. It is found that the PS shape considerably changes both while going from compounds of the second period to those of the third period, and during the system charge change in spite of isoelectronic nature of the considered compounds. Regularities of variations of relative stability of classical and bridge-type isomers (LMX2 and L(X)2M) for similar systems, when cations L+ and substituents X change in different rows, are predicted