Department of Physics, University of Connecticut, Storrs, Connecticut 06269, USA.
J Chem Phys. 2012 Jan 7;136(1):014306. doi: 10.1063/1.3672646.
Electronic structure calculations have been carried out for all possible alkali tetramers that can be formed from X(2) + X(2) → X(2)X(2), X(2) + Y(2) → X(2)Y(2), and XY + XY → X(2)Y(2) alkali dimer association reactions. Vibrationally stable rhombic (D(2h)) and planar (C(s)) structures are found for all possible tetramers formed from the alkali metals, Li to Cs. All tetramer formation reactions (from ground state singlet homonuclear or heteronuclear dimers) are found to be exothermic with binding energies ranging from 6282 cm(-1) for Li(2)Li(2) to 1985 cm(-1) for Cs(2)Cs(2). Extensive calculations, carried out at long-range for several reactant pairs, indicate that there are barrier-less pathways for the formation of tetramers from dimer association reactions. At low temperatures, direct formation of tetramers is unlikely, owing to the large exothermicity associated with these association reactions, but atom exchange reactions (X(2) + Y(2) ↔ XY + XY) are possible for some species.
已针对所有可能的碱四聚体进行了电子结构计算，这些四聚体可以通过以下三种碱二聚体缔合反应形成：X(2) + X(2) → X(2)X(2)、X(2) + Y(2) → X(2)Y(2)和 XY + XY → X(2)Y(2)。对于由碱金属 Li 到 Cs 形成的所有可能的四聚体，都发现了具有稳定振动的菱形(D(2h))和平面(C(s))结构。所有四聚体形成反应（来自基态单重同核或异核二聚体）均为放热反应，结合能范围从 Li(2)Li(2)的 6282 cm(-1)到 Cs(2)Cs(2)的 1985 cm(-1)。对于一些反应物对，进行了长程的广泛计算，表明从二聚体缔合反应形成四聚体存在无势垒途径。在低温下，由于这些缔合反应具有很大的放热性，直接形成四聚体不太可能，但对于某些物种，原子交换反应（X(2) + Y(2) ↔ XY + XY）是可能的。
