Physical and Theoretical Chemistry, Modeling and Simulation, Atomic and Molecular Physics, and Optics, Spectroscopy
20
Scopus Publications
349
Scholar Citations
13
Scholar h-index
15
Scholar i10-index
Scopus Publications
Effect of neighbouring molecules on ground-state properties of many-body polar linear rotor systems Tapas Sahoo, Gautam Gangopadhyay Molecular Physics, 2023 A path integral ground state approach has been used to estimate the ground-state energy and structural properties of hydrogen fluoride molecules pinned to a one-dimensional lattice. In the simulations, the molecules are assumed to be rigid, and only the continuous rotational degrees of freedom are considered. The constituents of a many-body system interact through the dipole-dipole interaction because the molecules have a permanent dipole moment. The workability of our approach has been demonstrated by estimating the ground-state energy, order parameter and nearest neighbour correlation for the systems of 2 and 3 HF molecules using quantum Monte Carlo simulations based on the path integral ground state methodology. The results agree satisfactorily with those obtained from exact Hamiltonian matrix diagonalization. In addition, the effect of neighbours on the ground state properties has been investigated for larger systems. The converged ground-state energy per neighbour as a function of inter-nuclear separation is considered to be the equation of state for the system.
A path integral ground state approach for asymmetric top rotors with nuclear spin symmetry: Application to water chains Tapas Sahoo, Tobias Serwatka, Pierre-Nicholas Roy Journal of Chemical Physics, 2021 A path integral ground state (PIGS) approach for the simulation of asymmetric top rotors is presented. The method is based on Monte Carlo sampling of angular degrees of freedom. A symmetry-adapted rotational density matrix is used to account for nuclear spin statistics. To illustrate the method, ground-state properties of collections of para-water molecules confined to a one-dimensional lattice are computed. Those include energetic and structural observables. An advantage of the PIGS method is that expectation values can be obtained directly since the square of the wavefunction is sampled during a simulation. To benchmark the method, ground state energies and orientational distributions are computed using exact diagonalization for a single para-water molecule in an external field using a finite basis of symmetric top eigenfunctions. Benchmark results are also provided for N = 2 para-water molecules pinned to lattice sites at various distances to sample the crossover from hydrogen bonding to the dipole–dipole interaction regime. Excellent agreement between the PIGS results and the finite basis set calculations is observed. A thorough analysis of the convergence in terms of the imaginary time propagation length and systematic Trotter error is performed. The PIGS approach is then applied to a chain of N = 11 water molecules, and an equation of state is constructed in terms of the intermolecular separation. Ordering effects are also studied, and a transition between hydrogen bonding to dipole–dipole alignment is observed. The method is scalable and can also be applied in higher dimensions.
Charge Transfer Processes for H + H 2+Reaction Employing Coupled 3D Wavepacket Approach on beyond Born-Oppenheimer Based Ab Initio Constructed Diabatic Potential Energy Surfaces Sandip Ghosh, Tapas Sahoo, Michael Baer, Satrajit Adhikari Journal of Physical Chemistry A, 2021 The dynamics of the H + H2+ reaction has been analyzed from the electronically first excited state of diabatic potential energy surfaces constructed by employing the Beyond Born-Oppenheimer theory [J. Chem. Phys. 2014, 141, 204306]. We have employed the coupled 3D time-dependent wavepacket formalism in hyperspherical coordinates for multisurface reactive scattering problems. To be specific, the charge transfer processes have been investigated extensively by calculating state-to-state as well as total reaction probabilities and integral cross sections, when the reaction process is initiated from the first excited electronic state (21A'). We have depicted the convergence profiles of reaction probabilities for the competing charge transfer processes, namely, reactive charge transfer (RCT) and nonreactive charge transfer (NRCT) processes for different total energies with respect to total angular momentum, J. Total and state-to-state integral cross sections are calculated as a function of total energy for the initial rovibrational state, namely, v = 0, j = 0 level of H2+ (2Σg+) molecule and are compared with previous theoretical calculations. Finally, we have calculated temperature-dependent rate constants using our presently evaluated cross sections and compared their average with the experimentally measured one.
A path integral ground state replica trick approach for the computation of entanglement entropy of dipolar linear rotors Tapas Sahoo, Dmitri Iouchtchenko, C. M. Herdman, Pierre-Nicholas Roy Journal of Chemical Physics, 2020 We calculate the second Rényi entanglement entropy for systems of interacting linear rotors in their ground state as a measure of entanglement for continuous rotational degrees of freedom. The entropy is defined in relation to the purity of a subsystem in a bipartite quantum system, and to compute it, we compare two sampling ensembles based on the path integral ground state (PIGS) formalism. This scheme centers on the replica trick and is aided by the ratio trick, both developed in this context by Hastings et al. [Phys. Rev. Lett. 104, 157201 (2010)]. We study a system composed of linear quantum rotors on a lattice in one dimension, interacting via an anisotropic dipole–dipole potential. The ground state second Rényi entropies estimated by PIGS are benchmarked against those from the density matrix renormalization group for various interaction strengths and system sizes. We find that the entropy grows with an increase in interaction strength, and for large enough systems, it appears to plateau near log(2). We posit that the limiting case of many strongly interacting rotors behaves akin to a lattice of two-level particles in a cat state, in which one naturally finds an entanglement entropy of log(2).
Beyond Born–Oppenheimer theory for spectroscopic and scattering processes Bijit Mukherjee, Koushik Naskar, Soumya Mukherjee, Sandip Ghosh, Tapas Sahoo, Satrajit Adhikari International Reviews in Physical Chemistry, 2019 We review our development on beyond Born–Oppenheimer (BBO) theory and its implementation on various models and realistic molecular processes as carried out over the last 15 years. The theoretical formulation leading to the BBO equations are thoroughly discussed with ab initio calculations. We have employed first principle based BBO theory not only to formulate single surface extended Born–Oppenheimer equation to understand the nature of nonadiabatic effect but also to construct accurate diabatic potential energy surfaces (PESs) for important spectroscopic systems, namely, NO radical, Na and K clusters, NO radical, benzene and 1,3,5-trifluorobenzene radical cations ( and ) as well as triatomic reactive scattering systems like and . The nonadiabatic phenomena like Jahn–Teller (JT), Renner–Teller, pseudo Jahn–Teller effects and the accidental conical intersections are the key players in dictating spectroscopic and reactive scattering profiles. The nature of diabatic coupling elements derived from ab initio data with BBO theory for molecular processes in Franck-Condon region has been analysed in the context of linearly and bilinearly coupled JT model Hamiltonian. The results obtained from quantum dynamical calculations on BBO based diabatic PESs of the above molecular systems are found to be in accord with available experimental outcomes.
Coupled 3D Time-Dependent Wave-Packet Approach in Hyperspherical Coordinates: The D++H2 Reaction on the Triple-Sheeted DMBE Potential Energy Surface Sandip Ghosh, Tapas Sahoo, Satrajit Adhikari, Rahul Sharma, António J. C. Varandas Journal of Physical Chemistry A, 2015 We implement a coupled three-dimensional (3D) time-dependent wave packet formalism for the 4D reactive scattering problem in hyperspherical coordinates on the accurate double many body expansion (DMBE) potential energy surface (PES) for the ground and first two singlet states (1(1)A', 2(1)A', and 3(1)A') to account for nonadiabatic processes in the D(+) + H2 reaction for both zero and nonzero values of the total angular momentum (J). As the long-range interactions in D(+) + H2 contribute significantly due to nonadiabatic effects, the convergence profiles of reaction probabilities for the reactive noncharge transfer (RNCT), nonreactive charge transfer (NRCT), and reactive charge transfer (RCT) processes are shown for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. The total and state-to-state cross sections are presented as a function of the collision energy for the initial rovibrational state v = 0, j = 0 of the diatom, and the calculated cross sections compared with other theoretical and experimental results.
The effect of surface temperature on H2/D2(v = 0, j = 0)-Ni(100) scattering processes Souvik Mandal, Tapas Sahoo, Sandip Ghosh, Satrajit Adhikari Molecular Physics, 2015 We carry out both four-dimensional (4D×2D) and six-dimensional (6D) quantum dynamics on a parametrically time- and temperature-dependent effective Hamiltonian for H2/D2(v = 0,j = 0)–Ni(100) collision process. Such an effective potential was derived within a theoretical framework of mean-field approximation by considering weakly correlated interaction between molecular degrees of freedom, phonon modes and electron– hole pair (elhp) coupling through a Hartree-product-type wave function, where the initial state distribution of the surface modes and elhp coupling were introduced through Bose– Einstein and Fermi– Dirac probability factor, respectively. The temperature-dependent dissociation and state-to-state transition probabilities for H2/D2(v = 0,j = 0)–Ni(100) system are depicted as a function of initial kinetic energ of the incoming diatom. Though such effect appears negligibly small for H2(v = 0,j = 0)–Ni(100) system, it is prominent in the case of D2(v = 0,j = 0)–Ni(100) collision. It appears that the change of dissociation and transition probabilities of D2 with the increase of surface temperature is exclusively dictated by the phonon modes directed along Z-axis, but the effect of elhp coupling particularly for transition probabilities is insignificant.
Second order classical perturbation theory for the sticking probability of heavy atoms scattered on surfaces Tapas Sahoo, Eli Pollak Journal of Chemical Physics, 2015 A second order classical perturbation theory is developed to calculate the sticking probability of a particle scattered from an uncorrugated thermal surface. An analytic expression for the temperature dependent energy loss of the particle to the surface is derived by employing a one-dimensional generalized Langevin equation. The surface temperature reduces the energy loss, since the thermal surface transfers energy to the particle. Using a Gaussian energy loss kernel and the multiple collision theory of Fan and Manson [J. Chem. Phys. 130, 064703 (2009)], enables the determination of the fraction of particles trapped on the surface after subsequent momentum reversals of the colliding particle. This then leads to an estimate of the trapping probability. The theory is tested for the model scattering of Ar on a LiF(100) surface. Comparison with numerical simulations shows excellent agreement of the analytical theory with simulations, provided that the energy loss is determined by the second order perturbation theory.
The effect of phonon modes and electron-hole pair couplings on molecule-surface scattering processes Souvik Mandal, Tapas Sahoo, Sandip Ghosh, Satrajit Adhikari Journal of Theoretical and Computational Chemistry, 2015 The effect of phonon modes and electron–hole pair (elhp) couplings at different surface temperature on D 2(v = 0, 1; j = 0)– Cu (111) collision has been explored by assuming weakly correlated interactions between molecular Degrees of Freedoms (DOFs) with surface modes and elhp excitations through a Hartree product type wavefunction, where the initial state distributions for the phonon modes and the elhp couplings are incorporated by using Bose–Einstein and Fermi–Dirac probability factors, respectively. We carry out four (4D⊗2D)- and six (6D)- dimensional quantum dynamics on such an effective Hamiltonian, and depict the calculated sticking/transition probabilities and energy transfer from molecule to the surface. The phonon modes slightly affect the sticking probability by broadening the profile, but the transition probability are substantially changed with respect to the rigid surface. On the contrary, the inclusion of elhp coupling along with phonon modes does not change the results much compared to the only phonon case.
The effect of surface temperature for the scattering of D2 (ν = 0, j = 0)-Cu(111) system : A spherical polar TDDVR approach Journal of the Indian Chemical Society, 2015
Effect of neighbouring molecules on ground-state properties of many-body polar linear rotor systems T Sahoo, G Gangopadhyay Molecular Physics 121 (24), e2242967 , 2023 2023 Citations: 2
Comparison of physical processes of atom-surface scattering computed by classical and quantum dynamics T Sahoo https://arxiv.org/abs/2306.17483v3 , 2023 2023
Effect of neighbouring molecules on ground-state properties of many-body polar linear rotor systems T Sahoo, G Gangopadhyay https://arxiv.org/abs/2305.17637 , 2023 2023 Citations: 2
A path integral ground state approach for asymmetric top rotors with nuclear spin symmetry: Application to water chains T Sahoo, T Serwatka, PN Roy The Journal of Chemical Physics 154 (24) , 2021 2021 Citations: 14
Charge Transfer Processes for H + H 2 + Reaction Employing Coupled 3D Wavepacket Approach on Beyond Born–Oppenheimer Based Ab Initio Constructed … S Ghosh, T Sahoo, M Baer, S Adhikari The Journal of Physical Chemistry A 125 (3), 731-745 , 2021 2021 Citations: 21
A path integral ground state replica trick approach for the computation of entanglement entropy of dipolar linear rotors T Sahoo, D Iouchtchenko, CM Herdman, PN Roy The Journal of Chemical Physics 152 (18) , 2020 2020 Citations: 17
Beyond Born–Oppenheimer theory for spectroscopic and scattering processes B Mukherjee, K Naskar, S Mukherjee, S Ghosh, T Sahoo, S Adhikari International Reviews in Physical Chemistry 38 (3-4), 287-341 , 2019 2019 Citations: 65
Coupled 3D Time-Dependent Wave-Packet Approach in Hyperspherical Coordinates: The D + +H 2 Reaction on the Triple-Sheeted DMBE Potential Energy Surface S Ghosh, T Sahoo, S Adhikari, R Sharma, AJC Varandas The Journal of Physical Chemistry A 119 (50), 12392-12403 , 2015 2015 Citations: 30
The effect of surface temperature on H2/D2 (v= 0, j= 0)–Ni (100) scattering processes S Mandal, T Sahoo, S Ghosh, S Adhikari Molecular Physics 113 (19-20), 3042-3056 , 2015 2015 Citations: 9
Second order classical perturbation theory for the sticking probability of heavy atoms scattered on surfaces T Sahoo, E Pollak The Journal of chemical physics 143 (6) , 2015 2015 Citations: 4
The effect of phonon modes and electron–hole pair couplings on molecule–surface scattering processes S Mandal, T Sahoo, S Ghosh, S Adhikari Journal of Theoretical and Computational Chemistry 14 (04), 1550028 , 2015 2015 Citations: 10
The effect of surface temperature for the scattering of D2 (v=0, j=0)-Cu(111) system : A spherical polar TDDVR approach S Mandal, T Sahoo, S Ghosh, S Adhikari J. Indian Chem. Soc. 92, 291-303 , 2015 2015
Low-temperature D++ H2 reaction: A time-dependent coupled wave-packet study in hyperspherical coordinates T Sahoo, S Ghosh, S Adhikari, R Sharma, AJC Varandas The Journal of Chemical Physics 142 (2) , 2015 2015 Citations: 33
Coupled 3D Time-Dependent Wave-Packet Approach in Hyperspherical Coordinates: Application to the Adiabatic Singlet-State(1 1 A′) D + + H 2 Reaction T Sahoo, S Ghosh, S Adhikari, R Sharma, AJC Varandas The Journal of Physical Chemistry A 118 (26), 4837-4850 , 2014 2014 Citations: 35
Nearly Linear Scalability of Time-Dependent Discrete Variable Representation (TDDVR) Method for the Dynamics of Multi-Surface Multi-Mode Hamiltonian BA Khan, S Sardar, T Sahoo, P Sarkar, S Adhikari Journal of Theoretical and Computational Chemistry 12 (05), 1350042 , 2013 2013 Citations: 10
Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: A simulated annealing based approach BK Shandilya, S Sen, T Sahoo, S Talukder, P Chaudhury, S Adhikari The Journal of Chemical Physics 139 (3) , 2013 2013 Citations: 19
Surface temperature effect on the scattering of D2 (v= 0, j= 0)-Cu (111) system T Sahoo, S Mukherjee, S Adhikari The Journal of Chemical Physics 136 (8) , 2012 2012 Citations: 13
Dressed adiabatic and diabatic potentials to study conical intersections for F+ H2 A Das, T Sahoo, D Mukhopadhyay, S Adhikari, M Baer The Journal of Chemical Physics 136 (5) , 2012 2012 Citations: 15
The effect of phonon modes on the D 2 ( v =0, j =0)–Cu(111) scattering processes T Sahoo, S Sardar, S Adhikari Physica Scripta 84 (2), 028105 , 2011 2011 Citations: 13
Effect of Surface Modes on the Six-Dimensional Molecule–Surface Scattering Dynamics of H 2 –Cu(100) and D 2 –Cu(111) Systems T Sahoo, S Sardar, P Mondal, B Sarkar, S Adhikari The Journal of Physical Chemistry A 115 (21), 5256-5273 , 2011 2011 Citations: 20
MOST CITED SCHOLAR PUBLICATIONS
Beyond Born–Oppenheimer theory for spectroscopic and scattering processes B Mukherjee, K Naskar, S Mukherjee, S Ghosh, T Sahoo, S Adhikari International Reviews in Physical Chemistry 38 (3-4), 287-341 , 2019 2019 Citations: 65
Coupled 3D Time-Dependent Wave-Packet Approach in Hyperspherical Coordinates: Application to the Adiabatic Singlet-State(1 1 A′) D + + H 2 Reaction T Sahoo, S Ghosh, S Adhikari, R Sharma, AJC Varandas The Journal of Physical Chemistry A 118 (26), 4837-4850 , 2014 2014 Citations: 35
Low-temperature D++ H2 reaction: A time-dependent coupled wave-packet study in hyperspherical coordinates T Sahoo, S Ghosh, S Adhikari, R Sharma, AJC Varandas The Journal of Chemical Physics 142 (2) , 2015 2015 Citations: 33
Coupled 3D Time-Dependent Wave-Packet Approach in Hyperspherical Coordinates: The D + +H 2 Reaction on the Triple-Sheeted DMBE Potential Energy Surface S Ghosh, T Sahoo, S Adhikari, R Sharma, AJC Varandas The Journal of Physical Chemistry A 119 (50), 12392-12403 , 2015 2015 Citations: 30
Charge Transfer Processes for H + H 2 + Reaction Employing Coupled 3D Wavepacket Approach on Beyond Born–Oppenheimer Based Ab Initio Constructed … S Ghosh, T Sahoo, M Baer, S Adhikari The Journal of Physical Chemistry A 125 (3), 731-745 , 2021 2021 Citations: 21
Effect of Surface Modes on the Six-Dimensional Molecule–Surface Scattering Dynamics of H 2 –Cu(100) and D 2 –Cu(111) Systems T Sahoo, S Sardar, P Mondal, B Sarkar, S Adhikari The Journal of Physical Chemistry A 115 (21), 5256-5273 , 2011 2011 Citations: 20
Selective bond breaking mediated by state specific vibrational excitation in model HOD molecule through optimized femtosecond IR pulse: A simulated annealing based approach BK Shandilya, S Sen, T Sahoo, S Talukder, P Chaudhury, S Adhikari The Journal of Chemical Physics 139 (3) , 2013 2013 Citations: 19
The effect of phonon modes on the H 2 (v, j)/D 2 (v, j)–Cu (1nn) scattering processes T Sahoo, S Sardar, S Adhikari Physical Chemistry Chemical Physics 13 (21), 10100-10110 , 2011 2011 Citations: 19
A path integral ground state replica trick approach for the computation of entanglement entropy of dipolar linear rotors T Sahoo, D Iouchtchenko, CM Herdman, PN Roy The Journal of Chemical Physics 152 (18) , 2020 2020 Citations: 17
Dressed adiabatic and diabatic potentials to study conical intersections for F+ H2 A Das, T Sahoo, D Mukhopadhyay, S Adhikari, M Baer The Journal of Chemical Physics 136 (5) , 2012 2012 Citations: 15
A path integral ground state approach for asymmetric top rotors with nuclear spin symmetry: Application to water chains T Sahoo, T Serwatka, PN Roy The Journal of Chemical Physics 154 (24) , 2021 2021 Citations: 14
Surface temperature effect on the scattering of D2 (v= 0, j= 0)-Cu (111) system T Sahoo, S Mukherjee, S Adhikari The Journal of Chemical Physics 136 (8) , 2012 2012 Citations: 13
The effect of phonon modes on the D 2 ( v =0, j =0)–Cu(111) scattering processes T Sahoo, S Sardar, S Adhikari Physica Scripta 84 (2), 028105 , 2011 2011 Citations: 13
The effect of phonon modes and electron–hole pair couplings on molecule–surface scattering processes S Mandal, T Sahoo, S Ghosh, S Adhikari Journal of Theoretical and Computational Chemistry 14 (04), 1550028 , 2015 2015 Citations: 10
Nearly Linear Scalability of Time-Dependent Discrete Variable Representation (TDDVR) Method for the Dynamics of Multi-Surface Multi-Mode Hamiltonian BA Khan, S Sardar, T Sahoo, P Sarkar, S Adhikari Journal of Theoretical and Computational Chemistry 12 (05), 1350042 , 2013 2013 Citations: 10
The effect of surface temperature on H2/D2 (v= 0, j= 0)–Ni (100) scattering processes S Mandal, T Sahoo, S Ghosh, S Adhikari Molecular Physics 113 (19-20), 3042-3056 , 2015 2015 Citations: 9
Second order classical perturbation theory for the sticking probability of heavy atoms scattered on surfaces T Sahoo, E Pollak The Journal of chemical physics 143 (6) , 2015 2015 Citations: 4
Effect of neighbouring molecules on ground-state properties of many-body polar linear rotor systems T Sahoo, G Gangopadhyay Molecular Physics 121 (24), e2242967 , 2023 2023 Citations: 2
Effect of neighbouring molecules on ground-state properties of many-body polar linear rotor systems T Sahoo, G Gangopadhyay https://arxiv.org/abs/2305.17637 , 2023 2023 Citations: 2
Comparison of physical processes of atom-surface scattering computed by classical and quantum dynamics T Sahoo https://arxiv.org/abs/2306.17483v3 , 2023 2023
