Sonjoy Majumder

Determination of conformational energy differences of propynlidyne isomers using the effective valence shell Hamiltonian method

We have applied the highly correlated ab initio effective valence shell Hamiltonian (Hv) method to determine the energy difference between the cyclic and linear isomers of propynlidyne (C3H). Calculations are also described for the vertical excitation energies, ionization potentials, electron affinities, dipole moments, oscillator strengths, and some harmonic vibrational frequencies, which are all determined using the third order Hv method. Computations at both the experimental and theoretically optimized geometries are used to illustrate the geometrical dependence of the computed properties. The Hv optimized geometry is obtained using a two-configurational reference function describing the two dominant resonance structures. Our third-order vertical excitation energy to the lowest excited state in the cyclic isomer, dipole moments, and ground state isomer conformational energy difference are all in good agreement with experiment and with other highly correlated many-body calculations. The computations for...

Relativistic calculations of the lifetimes and hyperfine structure constants in 67Zn

This work presents accurate ab initio determination of the magnetic dipole (Ml) and electric quadrupole (E2) hyperfine structure constants for the ground and a few low-lying excited states in 67 Zn + , which is one of the interesting systems in fundamental physics. The coupled-cluster (CC) theory within the relativistic framework has been used here in these calculations. Long-standing demands for a relativistic and highly correlated calculation like CC can be able to resolve the disagreements among the lifetime estimations reported previously for a few low-lying states of Zn + . The roles of different electron correlation effects in the determination of these quantities are discussed and their contributions are presented.

Effect of screening on spectroscopic properties of Li-like ions in a plasma environment

This work presents accurate {\it ab initio} investigations of various spectroscopic properties of a few Li-like ions in presence of a plasma environment within the Debye screening potential. The coupled-cluster theory in the relativistic framework has been employed to compute ionization potentials, excitation energies, electric dipole oscillator strengths, and electric quadrupole transition probabilities of Li-like C

Accurate Calculations of Interstellar Lines of Mg+ Using the Coupled Cluster Approach

^{3+}

ACCURATE ESTIMATIONS OF STELLAR AND INTERSTELLAR TRANSITION LINES OF TRIPLY IONIZED GERMANIUM

, N

Efficient treatment of the Hartree interaction in the relativistic Kohn-Sham problem

^{4+}

Relativistic coupled cluster calculations using hybrid basis functions

, and O

Influence of correlation effects on the magnetic dipole hyperfine interaction in the low-lying states of Ca+

^{5+}

Electric dipole transition amplitudes for 207Pb

ions. The unretarded Breit interaction has been implemented to increase the accuracy of the calculations. The effects of ion density and temperature on the ionization potentials, excitation energies, electric dipole oscillator strengths, and electric quadrupole transition probabilities have been investigated in the plasma environment. It is found that the plasma screening leads to a sharp decrease in the ionization potential as the screening strength increases. With increasing strength, the oscillator strengths associated with 2

Theoretical spectroscopic studies of the atomic transitions and lifetimes of low-lying states in Ti IV

s ^{2}S_{1/2}