• Manoj K Mishra

      Articles written in Journal of Chemical Sciences

    • Treatment of Be+ (1s− 1)2S Auger resonance with different decouplings of the dilated electron propagator

      Milan N Medikeri Manoj K Mishra

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      The diagonal 2ph-TDA and quasiparticle decouplings of the dilated electron propagator (based on an underlying bi-variational SCF) are utilized to calculate energy and width of the Be+(1s−1)2S Auger resonance for the first time. Comparison with experimental and other theoretical results reveals that the renormalized infinite order diagonal 2ph-TDA decoupling seems to offer a less balanced approach to the treatment of resonances than the second-order decoupling. The diagonal quasiparticle approximation to the self energy is seen to offer an effective and economic alternative to the non-diagonal propagator calculations.

    • Selective control of HOD photodissociation using CW lasers

      Manabendra Sarma S Adhikari Manoj K Mishra

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      Selective control of HOD photodissociation (H-O + D $\leftarrow$ HOD → H + O-D) has been theoretically investigated using CW lasers with appropriate carrier frequency and |0, 0$\rangle$, |0, 1$\rangle$ and |0, 2$\rangle$ with zero quantum of excitation in the O-H bond and zero, one and two quanta of excitation in the O-D bond as the initial states. Results indicate that the O-H bond in HOD can be selectively dissociated with a maximum flux of 87% in the H + O-D channel from the ground vibrational state |0, 0$\rangle$. For the O-D bond dissociation, it requires two quanta of excitation (|0, 2$\rangle$) in the O-D mode to obtain 83% flux in the H-O + D channel. Use of a two colour laser set-up in conjunction with the field optimized initial state (FOIST) scheme to obtain an optimal linear combination of |0, 0$\rangle$ and |0, 1$\rangle$ vibrational states as the initial state provides an additional 7% improvement to flux in the H-O + D channel as compared to that from the pure |0, 1$\rangle$ state.

    • Calculation of vibrational excitation cross-sections in resonant electron-molecule scattering using the time-dependent wave packet (TDWP) approach with application to the ${}^2\Pi$ CO- shape resonance

      Raman Kumar Singh Manabendra Sarma Ankit Jain Satrajit Adhikari Manoj K Mishra

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      Results from application of a new implementation of the time-dependent wave packet (TDWP) approach to the calculation of vibrational excitation cross-sections in resonant e-CO scattering are presented to examine its applicability in the treatment of e-molecule resonances. The results show that the SCF level local complex potential (LCP) in conjunction with the TDWP approach can reproduce experimental features quite satisfactorily.

    • Electronic structure analysis and vertical ionization energies of thiophene and ethynylthiophenes

      Raman K Singh Manoj K Mishra

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      Results from different decouplings of the electron propagator theory using MP2/6-311$g$ ($2df$, $2p$) and MP2/6-311$++g$ ($2df$, $2p$) optimized geometries have been performed to investigate first eight vertical ionization energies and the corresponding Dyson orbitals. The results computed are in good agreement with experimental ionization energies and help clear the ambiguities of experimental photoelectron spectrum (PES) assignments. Detailed examination of the 𝜋-orbital density distribution of Dyson orbitals provides clarity in PES assignments and new insights about the topology of ring 𝜋 and ethynyl $\pi_{c-c}$ electron density distribution which may be tapped for improved nonlinear optical/electrochemical response from the thiophenic conjugated polymers.

    • Vibrational excitation resulting from electron capture in LUMO of F2 and HCl - A treatment using the time-dependent wave packet approach

      Bhavesh K Shandilya Manabendra Sarma Satrajit Adhikari Manoj K Mishra

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      Vibrational excitation cross-sections $\sigma_{v_f \leftarrow v_i}$(𝐸) in resonant e-F2 and HCl scattering are calculated from transition matrix elements $T_{v_f \leftarrow v_i}$(𝐸) obtained using Fourier transform of the cross correlation function $\langle \phi_{v_f} (R) | \Phi_{v_i} (R, t) \rangle$. where $\Psi_{v_i} (R,t) \approx e^{i \hbar H_{AB^-}(R)t} \phi_{v_i} (R)$. Time evolution under the influence of the resonance anionic Hamiltonian H$_{AB^-}$ (AB=F2/HCl) is effected using Lanczos reduction technique followed by fast Fourier transform and the target (AB) vibrational eigenfunctions $\phi_{ν_i}$ (𝑅) and $\phi_{v_f}$ (𝑅) are calculated using Fourier grid Hamiltonian method applied to potential energy (PE) curve of the neutral target. The resulting vibrational excitation cross-sections provide reasonable agreement with experimental and other theoretical results.

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