Dibyendu Sardar

University of Colorado Boulder | CUB · Department of Physics

In this paper, we extensively study the electronic structure, interactions, and dynamics of the (MgCs)+ molecular ion. The exchanges between the alkaline atom and the low-energy cationic alkaline earths, which are important in the field of cold and ultracold quantum chemistry, are studied. We use an ab initio approach based on the formalism of non-...

A six-dimensional potential energy surface is constructed for the spin-polarized triplet state of CaF-CaF by ab initio calculations at the CCSD(T) level of theory, followed by Gaussian process interpolation. The potential is utilized to calculate the density of states for this bialkaline-earth-halogen system where we find the value 0.038 μK-1, impl...

In a recent experiment [P. Weckesser et al., Nature (London) 600, 429 (2021)], the quantum s-wave regime was attained for an alkali-metal and alkaline-earth atom-ion combination (LiBa+). We investigate possible outcomes from the interaction of this ion-atom pair at quantum regimes from a theoretical point of view. For this purpose, Born-Oppenheimer...

Studies on the interactions between an alkali atom and an alkaline earth ion at low energy are important in the field of cold chemistry. In this paper we, extensively, study the structure, interactions, and dynamics of (MgCs)$^+$ molecular ion. We use an ab initio approach based on the formalism of non-empirical pseudo-potential for Mg$^{2+}$ and C...

We propose a coherent optical method for creating negative refractive index (NRI) for a gaseous ensemble of ground-state polar molecules possessing both permanent electric and magnetic moments. Exploiting the pure rotational transition between the two lowest rotational levels of the ground vibrational state one can generate two dressed states of mi...

We propose a coherent optical method for creating negative refractive index (NRI) for a gaseous ensemble of ground-state polar molecules possessing both permanent electric and magnetic moments. Exploiting the pure rotational transition between the two lowest rotational levels of the ground vibrational state, one can generate two dressed states of m...

We develop a method for the calculation of multichannel wavefunctions in the spirit of quantum defect theory using numerically calculated reference functions. We have verified the efficacy of our method by calculating cold collisional properties of $^{85}$Rb and $^6$Li in the presence of external magnetic fields tuned across specific Feshbach reson...

In a previous paper [Deb and Agarwal 2014 Phys. Rev. A 90 063417], it was theoretically shown that, magneto-optical manipulation of low energy scattering resonances and atom-molecule transitions could lead to the formation of a bound state in continuum (BIC), provided there is no spontaneous emission. We find that even an exceedingly small spontane...

More than 65 years ago, Jost and Kohn (1952 Phys. Rev. 87, 977) derived an explicit expression for a class of short-range model potentials from a given effective range expansion with the s-wave scattering length as being negative. For as > 0, they calculated another class of short-range model potentials (Jost and Kohn 1953 Dan. Mat. Fys. Medd 27, n...

In a previous paper [B. Deb and G. S. Agarwal, Phys. Rev. A 90, 063417 (2014)], it was theoretically shown that, magneto-optical manipulation of low energy scattering resonances and atom-molecule transitions could lead to the formation of a bound state in continuum (BIC), provided there is no spontaneous emission. We find that even an exceedingly s...

The adiabatic potential energy curves, permanent and transition dipole moments (TDMs) of the highly-excited states of the MgK ⁺ molecular ion have been computed as a function of the inter-nuclear distance R. The results are obtained by an ab initio approach involving a non-empirical pseudo-potential for the Mg and K cores, correlation treatment for...

It is well-known that the zero-range contact potential approximation for the mean-field interaction of a many-atom system breaks down when the atoms interact through a scattering resonance. At present, there exists no standard model interaction potential that can accurately describe resonant or strong atom-atom interactions at low energy. More than...

In this theoretical work, we calculate molecular potential energy curves, spectroscopic constants and transition dipole moments for the ground (X²S⁺u, B²S⁺g) and first excited electronic states (A²Πu) of alkaline-earth molecular ion Mg2⁺. We consider an ab initio multi-reference configuration interaction method using an aug-cc-pv5z Gaussian basis s...

In this theoretical work, we calculate potential energy curves, spectroscopic parameters and transition dipole moments of molecular ions BeX⁺ (X=Na, K, Rb) composed of alkaline ion Be and alkali atom X with a quantum chemistry approach based on the pseudopotential model, Gaussian basis sets, effective core polarisation potentials and full configura...

We show theoretically that it is possible to form a cold molecular ion from a pair of colliding atom and ion at low energy by photoassociative two-photon Raman processes. We explore the possibility of stimulated Raman adiabatic passage (STIRAP) from the continuum of ion-atom scattering states to an ionic molecular state. We provide physical conditi...