Approximations for the inner branch of potential curves of diatomic molecules

Abstract

Three potential energy functions are examined with respect to their ability to reproduce the inner branch of the potential curve for 43 molecular states. Two of the states turn out to be unusual. In the remaining 41 cases, it is found that a potential proposed by the author gives the least error in 28 cases and is close to the least error in another six. The potential curves of NaAr(X) and XeCl(X) are very different from those of the other 41 states considered in this paper. The Born–Mayer potential appears to provide a reasonable representation of the inner branch of the potential curve for XeCl(X).

Valence State Atoms in Molecules. 5. Universal Scaling of the Inner Branch of Fifty RKR Potential Energy Curves. Comparison of the Valence State, Morse, and Rydberg Curves

“…As in section 3.1 above, the VS deviations are small and of random type. The ripples toward the end of the curves at small s are due to slight inaccuracies in the RKR data. , The complete set of deviations δ U , for 50 molecules, are recorded in Table . The average unsigned deviation, δ U of the VS−PEC for 50 molecules including metal halides and oxides is 1.14%.…”

“…Postulating also a “reduced” curvature at the minimum, i.e., a universal dimensionless force constant κ, the variable q and u ( q ) may be defined in terms of a parameter R ij , characterizing the bond between the atoms i and j . ,, Jenč has discussed several classes of reduced potentials . In the simpler case, first proposed by Frost and Musulin, FM, the parameter R ij is introduced only into the formula for q with By postulating R ij = 0 for H 2 and H 2 + , FM obtained κ = 4.00 and This may be compared to the reduced interatomic displacement q M appropriate for the Morse curve: ,,, and the definition of a scaling length l for the Rydberg PEC: Here, Δ = k e /2 D e is the Sutherland parameter; for s , see eq 10.…”

“…It also influences adhesion, cohesion, and chemisorption where similar potentials are operative . The theoretical importance of the repulsive terms and the different behavior of the various PECs at small and very small distances have been repeatedly emphasized. − Varshni 16 and Tellinghuisen 17 quantitatively assessed the performance of a number of PE functions in predicting the inner branch. Jenč and Brandt 18 used their reduced potential curve method , for extrapolations of RKR data on the repulsive branch.…”

Visualizing Chemical Reactions with X-rays

“…The Morse potentials are different in the electronic states X and A/A of I 2 , as are also the parameters D, b, and τ v describing them. The values of D and b were taken from the literature data for the X, A, and A states of I 2 [15]. To determine the parameter b, the relation ω 2 = (2D/µ)b 2 was employed with the frequency ω taken from [15].…”

“…The values of D and b were taken from the literature data for the X, A, and A states of I 2 [15]. To determine the parameter b, the relation ω 2 = (2D/µ)b 2 was employed with the frequency ω taken from [15]. Moreover, the "compact" state A/A was described writing…”