Ab initio Based Configuration Interaction Study of the Electronic States of InP

Abstract

Spectroscopic investigations of the low-lying electronic states of InP have been carried out by using multireference singles and doubles configuration interaction (MRDCI) method which includes relativistic effective core potentials (RECP) of the constituent atoms. There are at least 18 Λ-S states which are bound within 44 000 cm-1 of energy. Potential energy curves of 38 Λ-S states most of which correlate with lowest three dissociation limits have been computed. The dominant configuration of the ground state (X3Σ-) of the molecule is σ1 2 σ2 2 σ3 π2 with re ) 2.71 A and ωe ) 248 cm-1. The ground-state dissociation energy (De) of InP in the absence of the spin-orbit coupling is estimated to be 1.48 eV. However, after the inclusion of the spin-orbit interaction the De value is reduced to 1.33 eV. All 22 Λ-S states which converge with In(2P)+P(4S) and In(2P)+P(2D) asymptotes are allowed to interact in the spin-orbit CI calculations. Effects of the spin-orbit coupling on the spectroscopic constants of lowest eight Λ-S states are studied. The zerofield splitting of the X3Σstate of InP has been estimated from the spin-orbit CI results. Several avoided crossings in the potential energy curves of Ω states are reported. Transition probabilities of many electric dipole-allowed transitions have been computed. Transitions such as A3Π-X3Σ-, 3Σ+-3Π, 41Σ+-21Σ+, and A3Π-3Π are found to be more probable. The radiative lifetimes of six excited states, namely, 41Σ+, 23Σ+(II), 3Σ+, 21Π, A3Π, and 21Σ+ are estimated. The A3Π state is short-lived with a lifetime of about 190 ns. The AΠ0+ component survives from the predissociation. Seven allowed transitions from AΠ0+ with ∆Ω ) 0, (1 are studied. At the lowest vibrational level (ν′ ) 0), the lifetime of the AΠ0+ component is about 456 ns.