Theoretical study of the electronic spectrum of indium arsenide

The electronic spectrum of the indium arsenide molecule is studied by using an ab initio based multireference singles and doubles configuration intera ction (MRDCI) method. Relativistic effective core potentials (RECP) of In a nd As atoms are used in the calculations. Potential energy curves of 39 Del ta -S states of InAs have been reported. There are at least 19 Delta -S sta tes that are bound within 42 000 cm(-1) of energy. Spectroscopic constants (T-e, r(e), and omega (e)) of these states are estimated. The observed omeg a (e) for the ground state of the molecule agrees very well with the comput ed value, while the calculated transition energy of the (3)Pi excited state is underestimated. The ground-state dissociation energy (D-e) of InAs is c alculated to be 1.31 eV, which is comparable to that of InP. In the spin-or bit treatment, all 22 Delta -S states that correlate with the lowest two di ssociation limits are included. The computed zero-field splitting of the gr ound state of InAs agrees well with the observed value. Transition dipole m oments of many transitions are computed. Transition probabilities of A(3)Pi -X(3)Sigma (-), A(3)Pi-(3)Pi, (3)Sigma (+)-(3)Pi, 4(1)Sigma (+)-(1)Sigma ( +), and 4(1)Sigma (+)-2(1)Sigma (+) transitions are comparatively high. In the spin-orbit level six transitions from the A(3)Pi (+)(0) component, whic h survives the predissociation, are studied. The radiative lifetimes of exc ited states are also estimated. The spectroscopic properties of InAs have b een compared with those of the isovalent InP and InSb molecules.