Ab Initio Molecular Dynamics of Dimerization and Clustering in Alkali Metal Vapors

Abstract

Alkali metals are known to form dimers, trimers, and tetramers in their vapors. The mechanism and regularities of this phenomenon characterize the chemical behavior of the first group elements. We report ab initio molecular dynamics (AIMD) simulations of the alkali metal vapors and characterize their structural properties, including radial distribution functions and atomic cluster size distributions. AIMD confirms formation of Men, where n ranges from 2 to 4. High pressure sharply favors larger structures, whereas high temperature decreases their fraction. Heavier alkali metals maintain somewhat larger fractions of Me2, Me3, and Me4, relative to isolated atoms. A single atom is the most frequently observed structure in vapors, irrespective of the element and temperature. Due to technical difficulties of working with high temperatures and pressures in experiments, AIMD is the most affordable method of research. It provides valuable understanding of the chemical behavior of Li, Na, K, Rb, and Cs, which can lead to development of new chemical reactions involving these metals.

Superheating effects in line broadening of dense alkali vapors

“…At elevated temperatures in addition to monomers and dimers the coexistence of trimers and tetramers cannot be excluded. Their ionization behavior is not well investigated, but can definitely contribute to better source of free electrons [8].…”

Thin film liquid-vapor phase change phenomena over nano-porous substrates: A molecular dynamics perspective

“…In such cases Molecular Dynamics (MD) simulation is a fascinating and effective tool that considers all the physical phenomenon down to the atomic level which can contribute to find some crucial underlying mechanism. Using this MD simulation tool, some excellent studies have been done on the effect of heat transfer increment for evaporative phase change process [ [20] , [21] , [22] ] and especially on nanostructured surfaces [ [23] , [24] , [25] ]. Wang et al [ 24 ] developed a molecular dynamics simulation with an aluminum substrate decorated with nanostructures of different heights.…”

Ab initioGibbs ensemble Monte Carlo simulations of the liquid–vapor equilibrium and the critical point of sodium

“…[33][34][35] The critical densities and temperatures range from 0.175 to 0.3 g cm À3 in density and from 2485 to 2573 K in temperature. The sodium vapor is mainly an atomic gas without large clusters, 36 which thus greatly simplifies the structural constraints. Moreover, as FT-KS-DFT has proven to be reliable in the study of the condensed phases of sodium, 37,38 it may serve as an excellent testing ground to extend this application of FT-KS-DFT to cover the gaseous phase of a metal as well.…”