Abstract:
Spectroscopic constants for InCl and InCl3 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 InCl3 . The single-electron adjusted energy-consistent pseudopotential of
Igel-Mann et al. [Mol. Phys. 65, 1321 (1988)] 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 Pn5^nuP(R)un&,
where P(R) is the distance dependent molecular property. The P(R) curves show strong linear
behavior and therefore, the shape of the Pn curve is mostly determined by anharmonicity effects in
the InCl potential curve. For the vibrational ground state, |0>, the calculated property P0 deviates
only slightly from the property determined directly at the equilibrium distance, Pe . 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.