The accuracy of the pseudopotential approximation. I. An analysis of the spectroscopic constants for the electronic ground states of InCl and InCl3 using various three valence electron pseudopotentials for indium

Abstract

Spectroscopic constants for InCl and InCl 3 are determined by a coupled cluster procedure using relatively large basis sets and an energy-consistent semilocal three valence electron pseudopotential for indium. Possible errors within the pseudopotential approximation are discussed in detail by comparison of available pseudopotentials adjusted through different techniques. Core-polarization corrections and the deviation from a point core approximation are discussed. These corrections, however, do not lead to more accurate bond distances as compared to the experimental results. Differently adjusted three valence electron pseudopotentials yield quite different results for the bond distances of InCl and InCl 3 . The single-electron adjusted energy-consistent pseudopotential of Igel-Mann et al. ͓Mol. Phys. 65, 1321 ͑1988͔͒ yields the best results and therefore, this pseudopotential has been chosen for all further investigations on molecular properties. The Dunham parameters for InCl are calculated by solving the vibrational-rotational Schrödinger equation numerically. A finite field technique is used to determine the dipole moment and dipole-polarizability of diatomic InCl. The dependence of several molecular properties on the vibrational quantum state is determined by calculating the expectation value P n ϭ͗n͉P(R)͉n͘, where P(R) is the distance dependent molecular property. The P(R) curves show strong linear behavior and therefore, the shape of the P n curve is mostly determined by anharmonicity effects in the InCl potential curve. For the vibrational ground state, ͉0͘, the calculated property P 0 deviates only slightly from the property determined directly at the equilibrium distance, P e . There is in general satisfying agreement of our calculated values with available experimental results. However, it is concluded that in order to obtain very accurate spectroscopic constants a small core definition for indium has to be preferred.

Correlation consistent valence basis sets for use with the Stuttgart–Dresden–Bonn relativistic effective core potentials: The atoms Ga–Kr and In–Xe

“…A notable exception is constituted by a number of indium compounds, for which abnormally short bond distances are found. This problem has been noted previously for large-core pseudopotential calculations on heavy group III halides [51]. We attempted a number of calculations in which Bauschlicher's correlation-consistent basis set for In was used in conjunction with regular cc-pVnZ basis sets on H-Ar and SDB-cc-pVnZ on Ga-Kr and Sn-Xe.…”

Relativistic Pseudopotentional Incorporating Core/Valence Polarization and Nonlocal Effects

“…Ψ nkm (r,θ,φ) = r -1 P nk (r) χ km (θ,φ) (4) iQ nk (r) χ km (θ,φ) , where the angular factors are defined by χ km (θ,φ) = Σ 1/2 pσ=−1/2 C (λ 1/2 j; m -σ,σ) Y λ m-σ (θ,φ) φ 1/2 σ…”

Simulation of the A–X and B–X transition emission spectra of the InCl molecule in low pressure plasmas

“…However, Franck-Condon factors (F CF ) and vibrationally resolved transition probabilities A Four different sets of potential curves for the relevant states of InCl are avail-able: RKR potential curves [7], potential curves from two different quantum mechanical calculations [8,9] and those obtained by a pseudopotential approximation [10]. As the data for RKR potential curves are only available up to a vibrational quantum number of 16 they are fitted using Morse potential curves which can be derived using molecular constants taken from [7].…”