A convergent perturbation method using modified Lang Firsov transformation is developed for a two-site single-polaron system. The method is applicable for the entire range of the electron-phonon coupling strength from the antiadiabatic limit to the intermediate region of hopping. The single-electron energies, oscillator wave functions and correlation functions, calculated using this method, are in good agreement with the exact results.

The two-site single-polaron problem is studied within the perturbative expansions using different standard phonon basis obtained through the Lang Firsov (LF), modified LF (MLF) and modified LF transformation with squeezed phonon states (MLFS).The role of these convergent expansions using the above prescriptions in lowering the energy and in determining the correlation functions are compared for different values of coupling strength. The single-electron energy, oscillator wave functions and correlation functions are calculated for the same system. The applicability of different phonon basis in different regimes of the coupling strength as well as in different regimes of hopping are also discussed. *

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A two-site double exchange model with a single polaron is studied using a perturbation expansion based on the modified Lang-Firsov transformation. The antiferromagnetic to ferromagnetic transition and the crossover from small to large polaron are investigated for different values of the antiferromagnetic interaction (J) between the core spins and the hopping (t) of the itinerant electron. Effect of the external magnetic field on the small to large polaron crossover and on the polaronic kinetic energy are studied. When the magnetic transition and the small to large polaron crossover coincide for some suitable range of J/t, the magnetic field has very pronounced effect on the dynamics of polarons.

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A 109 Cd radioisotope-induced energy dispersive X-ray fluorescence (EDXRF) study has been performed on samples of cauliflower consisting of the flower, the leaves and the associated root soil. The cauliflowers are collected from farms near the main dumping site of municipal solid waste (MSW) in the city of Kolkata, India, and also from uncontaminated farms about 50 km away from the city. The systematic investigation is primarily aimed at achieving two correlated objectives. Firstly, a unified calibration approach is undertaken for the study tool viz., EDXRF spectrometer, through the use of same instrumental scattering constants for quantification in widely differing matrices like soil and plant. Quality control was done by quantitative reproduction of National Institute of Standards and Technology-Standard Reference Materials (NIST-SRMs). Subsequently, the second objective is to comparatively study elemental uptake in the cauliflower samples from contaminated and uncontaminated farms using the same calibration. This study suggests that the elemental concentrations in the root soils and leaves of the samples vary from farm to farm, whereby the concentrations of Cu, Zn and Pb in root soils of MSW-contaminated farms are higher by almost an order of magnitude compared to uncontaminated farms. But the most notable feature of this study is the strikingly similar elemental concentrations in the edible flower part of all samples irrespective of the soil type. Plots of the ratio of concentrations of elements in leaf to soil and in flower to leaf, observed from the present EDXRF study suggests that a preferential uptake of elements takes place at different stages.

The high spin states of 103 Ag have been populated through the 76 Ge( 35 Cl,␣4n␥) 103 Ag reaction using 132-MeV 35 Cl beam. The presence of a positive parity ground state band and two negative parity bands decaying predominantly by M1 transitions in 103 Ag has been confirmed. In addition, seven new crossover E2 transitions have been observed in the negative parity bands. The experimental B(M 1)/B(E2) ratios are compared with the values obtained from the Dönau geometric formula for the negative parity bands based on single particle configurations assigned from signature arguments. These ratios are also compared to those obtained from the hybrid version of tilted axis cranking. A systematic study of odd-Ag isotopes seems to indicate that the signature symmetry is retained in 103 Ag due to the shallow tilted minimum.