Calculations Of Potential Energy Curves Research Articles

Calculation of potential energy curves for the ground state of the hydrogen molecule

Potential energy curves for the X1σ g + state of H2 are calculated from three wave functions which, in spite of their conceptual simplicity, yield results of remarkable accuracy. The three functions yield 87·06, 91·07 and 93·14 per cent of the observed binding energy, and provide an accurate description of the system over a wide range of nuclear separations. The fundamental vibration frequency is calculated for each curve, and the long-range behaviour of the wave functions is examined.

Calculation of potential energy curves for S2 perturbed by a frozen inert gas matrix environment

When S2 is trapped in a frozen inert gas matrix, both the equilibrium internuclear distance re and the vibrational parameter ωe are perturbed by the matrix environment. If it is assumed that the Morse potential adequately represents the lowest part of the potential energy curve, the perturbation of re can be related to the perturbation of ωe as follows: Δ re=−constant Δ ωe. The validity of this result is demonstrated by the fact that, if experimental values of Δ ωe are used to calculate predicted values of Δ re, these predicted values are in excellent agreement with the experimental results.

Ab Initio Calculation of Potential Energy Curves for the Ion Molecule Reaction O++N2 → NO+ + N

Configuration interaction calculations verified an earlier hypothesis that the experimentally observed apparently anomalous behavior of the O++N2 → NO+ + N reaction is due to the symmetry and spin restrictions which prohibit the ground state reactants or products from correlating directly with the ground state intermediate. Complex symmetry adapted functions were used, and all single and double excitations were included for the ground and first excited Πi2 states, the lowest and second 2Σ+ states, the Π4 state and the 4Σ- state of the intermediate NNO+ for two cuts through the potential surface close to the reaction path. The number of configurations included were: Πi2 (123), 2Σ+ (177), 4Π (1349) and 4Σ- (1310). Analyses of the first order CI density matrices at large distances in terms of their ``fragmental'' MO's (or AO's) verified that the 4Σ- NNO+ state was formed from the ground state reactants O+(4Su) + N2(1Σg+) and that it separated into ground state products NO+(1Σ+) + N(4Su). The positions of other electronic states of NNO+ were well substantiated in agreement with photoelectron spectroscopic measurements. The calculated potential energy curves show an even greater wealth of structure than would have been anticipated prior to such a detailed computation. The most significant conclusion of the present research is the unambiguous confirmation of the overriding role that spin and symmetry restrictions play in any type of collisional process.

The electronic structure of HF+

Ab initio self-consistent field calculations of potential energy curves for the ground and first excited states of HF+ have been performed. The excited A2 Sigma + state is found to be bound, in agreement with the most recent experimental results. Qualitative arguments suggesting that the Hartree-Fock potential curves dissociate to the correct atomic limits are borne out by the calculations. A previous suggestion that interaction of the ground state X2 Pi with an excited state significantly affects the shape of the curve is not supported. Calculations have also been made of the perturbations between the lowest states due to spin-orbit interactions.

Application of the extended hückel theory to the calculation of potential energy curves for the proton motion in the [NH 3 + HCl] system

Potential energy curves for the proton motion in the [NH 3, HCl] system were calculated for five different N⋯ Cl distances, using the Extended Hückel Method. At large distances the potential energy curves have two minima with the one of lower energy at the chlorine atom; this is a characteristic of hydrogen bonding. At short distance the potential energy curve has one minimum at the nitrogen atom indicating the formation of the NH 4Cl molecule.

The calculation of potential energy curves of diatomic molecules: Application to halogen molecules

Methods for computing the vibrational turning points of diatomic molecules are summarized. An extension of the technique described by Vanderslice et al. is used to derive simple analytical expressions for calculation of the turning points from spectroscopic data. For most molecular states, the method gives results in agreement with those from sophisticated numerical procedures. Recently available spectroscopic data have been used to determine the potential energy curves for the 1∑ + g and 3Π(0 + u ) states of Cl 2 and Br 2.

Simple energy eigenfunctions for Li 2 and LiH

The use of an orbital parameter which varies with internuolear distance is tested by the calculation of potential energy curves of Li 2 and LiH in a Heitler-London approximation. The best method of choosing the molecular orbital parameter is discussed. The values of the dissociation energies obtained are compared to similar calculations which determined the orbital parameter in a different manner.