Bhanu Pratap Das

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A relativistic many-body theory for the electric dipole moment (EDM) of paramagnetic atoms arising from the electric dipole moment of the electron is presented and implemented. The relativistic coupled-cluster method with single and double excitations (RCCSD) using the Dirac-Coulomb Hamiltonian and a weak parity and time reversal violating interaction to(More)
We report the result of our ab initio calculation of the 6s2S1/2-->5d2D3/2 parity nonconserving electric dipole transition amplitude in 137Ba+ based on relativistic coupled-cluster theory. Considering single, double, and partial triple excitations, we have achieved an accuracy of less than 1%. If the accuracy of our calculation can be matched by the(More)
The electric dipole moment of atomic 199Hg induced by the nuclear Schiff moment and the tensor-pseudotensor electron-nucleus interactions are calculated. For this, we develop and employ a novel method based on the relativistic coupled-cluster theory. The results of our theoretical calculations, combined with the latest experimental result of the 199Hg(More)
Mihály Kállay,1 H. S. Nataraj,1 B. K. Sahoo,2 B. P. Das,3 and Lucas Visscher4 1Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest P.O. Box 91, H-1521 Hungary 2Theoretical Physics Division, Physical Research Laboratory, Ahmedabad 380009, India 3Indian Institute of Astrophysics, 560034 Bangalore,(More)
The existence of intrinsic electric dipole moment(EDM) of an atom implies simultaneous parity and time reversal violation. Within the standard model(SM) of particle physics tensor-pseudotensor(T-PT)interaction is not allowed. Combining the experimental results of an EDM measurement with a closed-shell atom with theoretical values, an estimate of coupling(More)
We present a new hybrid method to solve the relativistic Hartree-Fock-Roothan equations where the oneand two-electron radial integrals are evaluated numerically by defining the basis functions on a grid. This procedure reduces the computational costs in the evaluation of two-electron radial integrals. The orbitals generated by this method are employed to(More)
Heavy polar diatomic molecules are the primary tools for searching for the T-violating permanent electric dipole moment of the electron (eEDM). Valence electrons in some molecules experience extremely large effective electric fields due to relativistic interactions. These large effective electric fields are crucial to the success of polar-molecule-based(More)
The electric dipole moment (EDM) enhancement factor of atomic Tl is of considerable interest as it has been used in determining the most accurate limit on the electron EDM to date. However, its value varies from -179 to -1041 in different approximations. In view of the large uncertainties associated with many of these calculations, we perform an accurate(More)
Quantum phase transitions in ultracold atoms provide important insights into the behaviour of matter at very low temperatures [1, 2, 3, 4]. An important example of this class of transitions is the transition from a superfluid(SF) to a Mott insulator(MI) which has been observed in cold bosonic atoms in 3D optical lattices [5, 6] as predicted by Jaksch et al(More)