arXiv subjects

Ankush Thakur

Publications and source records attributed to Ankush Thakur.

4 recordsLinked to original sources

arXiv2026

Relativistic KRCI calculations of symmetry violating interaction constants for YbX (X: Cu, Ag and Au) molecules

The present work reports the parity ($\mathcal{P}$)-odd and time-reversal ($\mathcal{T}$)-odd interaction constants for the ground electronic state, X$^2Σ^{+}_{1/2}$, of YbX, X: Cu, Ag and Au molecules. The reported results have been calculated using the Kramers-restricted configuration interaction method limited to single and double excitations, in conjunction with relativistic core-valence double-, triple-, and quadruple-zeta quality basis sets, within a four-component relativistic framework. The computed results for the symmetry violating properties have been compared with the available results in the literature. Further, the parallel and perpendicular components of the hyperfine structure constants for the constituent atoms in YbX molecules are reported here for the first time.

physics.atom-ph↗

arXiv2025

Study of ground state electronic structure of XH$^+$ (X : Cd, Hg and Yb) molecular ions via coupled-cluster approach

The present work reports the spectroscopic parameters and molecular properties for the ground electronic state, $^1Σ^+$, of CdH$^+$, HgH$^{+}$, and YbH$^{+}$ molecular ions. We have used the state-of-the-art relativistic coupled cluster method together with the relativistic core-valence triple- and quadruple zeta quality basis sets for the calculation of structural parameters. The computed results have been extrapolated to the complete basis set limit using a two-point polynomial fit. The reliability of the results has been confirmed by their remarkable agreement with existing experimental and theoretical values. Further, we have calculated the relevant vibrational parameters by solving the vibrational Schrödinger equation using the potential energy curve and the permanent dipole moment curve of the electronic ground state. Subsequently, the lifetimes of the vibrational states have been determined by calculating the spontaneous and black-body radiation (BBR) induced transition rates. At room temperature, the lifetimes of the lowest ro-vibrational state ($v$ = $0$, $J$ = $0$) due to BBR-induced transitions are estimated to be $98.48$\,s for CdH$^+$, $204.85$\,s for HgH$^+$, and $1250.28$\,s for YbH$^+$. Additionally, the rotational energies within each vibrational state are also calculated in this work.

physics.atom-ph↗

arXiv2025

Ab initio calculations of diatomic constants and ro-vibrational parameters for the ground state of singly charged aluminium monohalides

We report electronic, vibrational, and rotational spectroscopic parameters for the ground state, X$^2Σ^{+}$, of singly charged aluminium monohalides, employing single-reference coupled-cluster theory with single and double excitations (CCSD) together with the relativistic basis sets. Higher order correlation effects coming from triple excitations are treated using perturbative CCSD(T) approach. Most of the molecular ions in the AlX$^+$ series, particularly barring the first two, have been studied here for the first time for their ground state electronic and vibrational structure. The vibrational parameters have been calculated by solving the vibrational Schrödinger equation utilizing potential energy curves and permanent dipole moment curves. Further, spontaneous and black-body radiation induced lifetimes have also been computed using relative energy separation and the transition dipole moments between the vibrational levels. The lifetimes of the lowest ro-vibrational states are found to be 10.63 s, 40.39 s, 23.13 s, 31.26 s, 13.43 s, and 8.08 s for the AlF$^+$, AlCl$^+$, AlBr$^+$, AlI$^+$, AlAt$^+$, and AlTs$^+$ ions, respectively. Furthermore, the rotational parameters such as Einstein coefficients and Franck-Condon factors for the lowest six vibrational states are also computed and reported in this work.

physics.atom-ph↗

arXiv2024

Relativistic coupled-cluster calculations for the molecular properties of AlX$^+$ (X: F, Cl, Br, I, At and Ts) ions

In this article, the molecular permanent electric dipole moments and components of static dipole polarizabilities for the electronic ground state of singly charged aluminum monohalides are reported. The coupled-cluster method by considering single and double excitations (CCSD) together with relativistic Dyall basis sets have been used to carry out these molecular property calculations. The contribution from triple excitations are incorporated through perturbative triples (CCSD(T)). The results from a series of progressively larger basis sets are extrapolated to the complete basis set limit. Further, the role of correlation and relativistic effects, and also the effect of augmentation over the considered basis sets on the valence molecular properties are studied. Our results are compared with those available in the literature.

physics.atom-ph↗