Simple Three-Parameter Model Potential for Diatomic Systems: From Weakly and Strongly Bound Molecules to Metastable Molecular Ions

Abstract

Based on a simplest molecular orbital theory of H + 2 , a three-parameter model potential function is proposed to describe ground-state diatomic systems with closed-shell and/or S-type valence-shell constituents over a significantly wide range of internuclear distances. More than 200 weakly and strongly bound diatomics have been studied, including neutral and singly-charged diatomics (e.g., H2, Li2, LiH, Cd2, Na + 2 , and RbH − ), long-range bound diatomics (e.g., NaAr, CdNe, He2, CaHe, SrHe, and BaHe), metastable molecular dications (e.g., BeH++ , AlH ++ , Mg ++ 2 , and LiBa ++ ), and molecular trications (e.g., YHe+++ and ScHe +++ ).PACS numbers: 34.20.-b, 33.15.-e, 21.45.+v, 36.40.-c, 83.10.-y, 82.20.-w Modeling the interaction potential of diatomic systems is of fundamental importance to many issues [1,2,3,4,5,6,7,8], including atom-atom collisions, molecular spectroscopy, prediction of cluster structures, molecular dynamics simulation, chemical reactivity, matter-wave interferometry, and transport properties for more complex systems. Also of great interest are the potential functions for long-lived metastable doubly-or multiplycharged ions [9] that are relevant to high-density energy storage materials and to characterization and analytical methods for biosystems.Modern spectroscopy, diffraction, and scattering techniques [1, 3] provide a direct experimental approach to studies of interaction potentials of diatomic systems. In particular, diatomic potentials can be inferred from the spectroscopy data by three general approaches [10]: (i) the Wentzel-Kramers-Brillouin (WKB) Rydberg-KleinRees (RKR) method, (ii) the WKB-based Dunham approach, and (iii) semiempirical or empirical procedures. On the theoretical side, a diatomic potential curve may be predicted directly by ab initio calculations [11] and quantum Monte Carlo simulations [12]. These theoretical methods can, in principle, be very accurate when sufficient electronic configurations are included in the calculations, but can be prohibitively expensive in weakly bound systems [2] and/or many-electron systems [3].Numerous attempts to analytically model diatomic potentials have been made [3,5,10,13,14,15,16]. The well-known potential functions include Morse, Born-Mayer, Hulburt-Hirschfelder, Rosen-Morse, Rydberg, Pöschl-Teller, Linnett, Frost-Musulin, Varshni III, Lippincott, Lennard-Jones, and Maitland-Smith potentials [3,10], as well as the celebrated Tang-Toennies potential [5] and the recently proposed Morse-based potentials [13]. These potentials usually aim to describe either strongly or weakly bound, neutral or singlycharged diatomics and often lose their validity for either small or relatively large internuclear distance (denoted R hereafter). Thus, recent effort has been devoted to the construction of hybrid potentials, which use different functions for different interaction regions of The goal of this Letter is twofold. First, we propose a molecular-orbital theory based approach to obtain a very simple analytical potential of diatomic systems. ...

Electron and nuclear spin polarization in Rb-Xe spin-exchange optical hyperpolarization

“…The obtained potential well depth, D e = 142.26 K, of our best theoretical Rb-Xe PEC agrees to some extent with the literature value of D e of 125.36 K by Patil [63], who used a combination of theoretical calculations and empirical values for some of the parameters, and very well with the value of 143.36 K from Refs. [64,65], which employed first-principles calculations. For the equilibrium distance R e , the values of 5.4082Å [63,64] and 5.4248Å [65] have been obtained, which should be contrasted with our present result, R e = 5.3674Å.…”

“…[64,65], which employed first-principles calculations. For the equilibrium distance R e , the values of 5.4082Å [63,64] and 5.4248Å [65] have been obtained, which should be contrasted with our present result, R e = 5.3674Å. In conclusion, as a secondary result of this study, probably one of the best theoretical PECs for the Rb-Xe system has been produced.…”

Molecular Spinless Energies of the Morse Potential Energy Model

“…Diatomic potential energy functions have been applied in various issues, such as atom-atom collisions, molecular spectroscopy, molecular dynamics simulation, chemical reactivity, and transport properties for more complex systems. 16 Alhaidari et al 17 pointed out that one can yield a nonrelativistic limit with a potential function 2V(r) from the Klein-Gordon equation with the equal scalar potential S(r) and vector potential V(r). In Ref.…”

Generalization of the Badger Rule Based on the Use of Adiabatic Vibrational Modes

“…Attempts have been made to verify and rationalize these relationships via model potentials for diatomics as, for example, Morse potentials, modified Morse potentials, doublereciprocal potentials (see entry 13, Table 4.1), single-reciprocal exponential potentials (entry 15, Table 4.1), or more complex forms of the potential (entry 29, Table 4.1). These relationships eventually led to the formulation of universal diatomic potentials [68,69] that attempt to define energy and spectroscopic properties of a universal bond, which can be considered the equivalent of the hydrogen atom in atom spectroscopy [70]. Clearly, the derivation and rationalization of fundamental relationships between various bond properties led to a better understanding of the chemical bond.…”