Surya Chattopadhyaya

Theoretical investigation of electronic states and spectroscopic properties of tellurium selenide molecule employing relativistic effective core potentials

Ab initio based relativistic configuration interaction calculations have been performed to study the electronic states and spectroscopic properties of tellurium selenide (TeSe) - the heaviest heteronuclear diatomic group 16-16 molecule. Potential energy curves of several spin-excluded (Λ-S) electronic states of TeSe have been constructed and spectroscopic constants of low-lying bound Λ-S states within 3.85 eV are reported in the first stage of calculations. The X(3)Σ(-), a(1)Δ and b(1)Σ(+) are found as the ground, first excited and second excited state, respectively, at the Λ-S level and all these three states are mainly dominated by …π(4)π(*2) configuration. The computed ground state dissociation energy is in very good agreement with the experimental results. In the next stage of calculations, effects of spin-orbit coupling on the potential energy curves and spectroscopic properties of the species are investigated in details and compared with the existing experimental results. After inclusion of spin-orbit coupling the X(3)(1)Σ(-)(0(+)) is found as the ground-state spin component of TeSe. The computed spin-orbit splitting between two components of X(3)Σ(-) state is 1285 cm(-1). Also, significant amount of spin-orbit splitting are found between spin-orbit components (Ω-components) of several other excited states. Transition moments of some important spin-allowed and spin-forbidden transitions are calculated from configuration interaction wave functions. The spin-allowed transition B(3)Σ(-)-X(3)Σ(-) and spin-forbidden transition b(1)Σ(+)(0(+))-X(3)(1)Σ(-)(0(+)) are found to be the strongest in their respective categories. Electric dipole moments of all the bound Λ-S states along with those of the two Ω-components of X(3)Σ(-) are also calculated in the present study.

Theoretical studies of the electronic spectrum of tellurium monosulfide

Ab initio based multireference singles and doubles configuration interaction (MRDCI) study including spin-orbit coupling is carried out to explore the electronic structure and spectroscopic properties of tellurium monosulfide (TeS) molecule by employing relativistic effective core potentials (RECP) and suitable Gaussian basis sets of the constituent atoms. Potential energy curves correlating with the lowest and second dissociation limit are constructed and spectroscopic constants (T(e), r(e), and ω(e)) of several low-lying bound Λ-S electronic states up to 3.68 eV of energy are computed. The binding energies and electric dipole moments (μ(e)) of the ground and the low-lying excited Λ-S states are also computed. The effects of the spin-orbit coupling on the electronic spectrum of the species are studied in details and compared with the available data. The transition probabilities of some dipole-allowed and spin-forbidden transitions are computed and radiative lifetimes of some excited states at lowest vibrational level are estimated from the transition probability data.

Configuration interaction study of the electronic states and spectroscopic properties of selenium monoxide.

The electronic spectrum of the selenium monoxide (SeO) molecule has been studied theoretically by using ab initio based multireference singles and doubles configuration interaction (MRDCI) methodology, which includes relativistic effective core potentials (RECP) and suitable Gaussian basis sets of the atoms. Potential energy curves of several electronic states correlating with the lowest and second dissociation limit are constructed. Spectroscopic parameters, namely Te, re, and ωe of 10 bound Λ-S states of the molecule within 4.71 eV are estimated and compared with the available data. In addition, binding energies of the ground and some excited states are computed. The changes in the potential energy curves and spectroscopic properties after the inclusion of the spin-orbit coupling are discussed and also compared with the available data. Transition probabilities of some dipole-allowed and spin forbidden transitions are estimated and radiative lifetimes of some excited states are reported. Dipole moments of some low-lying Λ-S states as a function of bond distance have also been computed.

Effects of spin–orbit coupling on the electronic states and spectroscopic properties of diatomic SeS

The electronic states and spectroscopic properties of selenium monosulfide (78Se32S) have been studied using relativistic configuration interaction methodology that includes effective core potentials of the constituent atoms. Potential energy curves of several spin-excluded (Λ−S) electronic states have been constructed and spectroscopic constants of low-lying bound Λ−S states within 5.1 eV are reported in the first stage of the calculations. In the next stage, the spin–orbit interaction has been incorporated and its effects on the potential energy curves and spectroscopic properties of the species have been investigated in detail. After the inclusion of spin–orbit coupling, the is identified as the spin–orbit (Ω) ground state of the species. The transition moments of several important dipole-allowed and spin-forbidden transitions are calculated and the radiative lifetimes of the excited states involved in the respective transitions are computed. Electric dipole moments (μ z) for some low-lying bound Λ−S states as well as a few low-lying spin–orbit states (Ω-states) are also calculated in the present study.

Electronic states and spectroscopic properties of MgH in absence and presence of spin–orbit coupling − a configuration interaction study

ABSTRACT Electronic spectrum of astrophysically important molecule magnesium hydride (MgH) has been studied using configuration interaction methodology excluding and including spin–orbit coupling. Potential energy curves of several spin-independent (Λ−S) electronic states have been constructed and spectroscopic constants of low-lying bound Λ−S states within 8.2 eV of term energy are reported in the first stage of calculations. The X2Σ+ is identified as the ground state in the Λ−S level. In the subsequent stage, the spin–orbit interaction has been incorporated and its effects on the potential energy curves and spectroscopic features of different electronic states of the species have been investigated. The X2Σ+1/2 is identified as the spin–orbit (Ω) ground state of the species. Transition moments of several dipole-allowed transitions are computed in both the stages and radiative lifetimes of the corresponding excited states are computed. Electric dipole moments (µ) for a number of low-lying bound Λ−S states as well as several low-lying Ω-states are also calculated in the present study.