Strong binding of carbon monoxide (CO) and dinitrogen (N) by MB (M = Co, Rh, Ir) clusters results in a spinning umbrella-like structure. For OCMB and NNMB complexes, the bond dissociation energy values range within 50.3-67.7 kcal/mol and 25.9-35.7 kcal/mol, respectively, with the maximum value obtained in Ir followed by that in Co and Rh analogues. COMB complex is significantly less stable than the corresponding C-side bonded isomer. The associated dissociation processes for OCMB and NNMB into CO or N and MB are highly endergonic in nature at 298 K, implying their high thermochemical stability with respect to dissociation. In OCMB and NNMB complexes, the C-O and N-N bonds are found to be elongated by 0.022-0.035 Å along with a large red-shift in the corresponding stretching frequencies, highlighting the occurrence of bond activation therein toward further reactivity due to complexation. The obtained red-shift is explained by the dominance of L←M π-back-donation (L = CO, OC, NN) over L→M σ-donation. The binding of L enhances the energy barrier for the rotation of the inner B unit within the outer B ring by 0.4-1.8 kcal/mol, which can be explained by a reduction in the distance of the longest bond between inner B and outer B rings upon complexation. A good correlation is found between the change in rotational barrier relative to that in MB and the energy associated with the L→M σ-donation. Born-Oppenheimer molecular dynamics simulations further support that the M-L bonds in the studied systems are kinetically stable enough to retain the original forms during the internal rotation of inner B unit.

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The efficacy of B borospherene to act as a host for noble gas atoms is explored via density functional theory based computations. Although the Ng@B complexes are thermochemically unstable with respect to dissociation into free Ng and B, it does not rule out their viability as all the systems possess a high activation free energy barrier (84.7-206.3 kcal mol). Therefore, once they are formed, it is hard to take out the Ng atom. Two Ng atoms can also be incorporated within B for the lighter Ng atoms (He and Ne). In fact, the destabilization offered by the encapsulation of one and two He atoms and one Ne atom inside B is significantly less than that in experimentally synthesized He@CH, highlighting their greater possibility for synthesis. Although Ar and Kr encapsulated B systems are very much destabilized by the repulsive interaction between Ng and B, an inspection of the bonding situation reveals that the confinement can even induce some degree of covalent interaction between two otherwise non-bonded Ng atoms. Ng atoms transfer electrons towards B which is smaller for lighter Ng atoms and gradually increases along He to Rn. Even if the electrostatic interaction between Ng and B is the most predominant term in these systems, the extent of the orbital interaction is also considerable. However, the very large Pauli repulsion counterbalances the attractive interaction, eventually turning the interaction repulsive in nature. Ng@B also shows dynamical behaviour involving continuous exchange between hexagonal and heptagonal holes, similar to the host cage, as understood from the very little variation in the activation barrier because of the Ng encapsulation. Furthermore, sandwich complexes like [(η-CMe)Fe(η-B)] and [(η-CMe)Fe(η-B)] are noted to be viable with the latter being slightly more stable than the former. The encapsulation of Xe slightly improves the dissociation energy associated with the decomposition into Xe@B and [Fe(η-CMe)] compared to that in the bare one.

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The behavior of a driven symmetric triple well potential has been studied by developing an algorithm where the well‐established Bohmian mechanics and time‐dependent Fourier Grid Hamiltonian method are incorporated and the quantum theory of motion (QTM) phase space structures of the particle are constructed, both in “nonclassical” and “classical” limits. Comparison of QTM phase space structures with their classical analogues shows both similarity as well as dissimilarities. The temporal nature and the spatial symmetry of applied perturbation play crucial roles in having similar phase space structures. © 2016 Wiley Periodicals, Inc.

The orbital free density functional theory and the single density equation approach are formally equivalent. An orbital free density based quantum dynamical strategy is used to study the quantum-classical correspondence in both weakly and strongly coupled van der Pol and Duffing oscillators in the presence of an external electric field in one dimension. The resulting quantum hydrodynamic equations of motion are solved through an implicit Euler type real space method involving a moving weighted least square technique. The Lagrangian framework used here allows the numerical grid points to follow the wave packet trajectory. The associated classical equations of motion are solved using a sixth order Runge-Kutta method and the Ehrenfest dynamics is followed through the solution of the time dependent Schrodinger equation using a time dependent Fourier Grid Hamiltonian technique. Various diagnostics reveal a close parallelism between classical regular as well as chaotic dynamics and that obtained from the Bohmian mechanics.

We demonstrate that one can exhaustively determine the n‐bound eigenstates of a Hamiltonian H by constructing a sequence of supersymmetric (SUSY) partner Hamiltonians and invoking a time‐dependent quantum adiabatic switching algorithm for passage from the ground state of one to the other. The ground states of the initial pair H(0) and H(1) are constructed by solving the Riccati equation for the superpotential ϕ(0) for H(0) and adiabatically switching from the ground state Ψ 0(0) of H(0) to the ground state Ψ 0(1) of H(1). The charge operator Q 0+ is then used to recover the first excited state Ψ 1(0) of H(0). The procedure is repeated for the ground states of SUSY pairs H(n + 1) and H(n + 2), and appropriate charge operators lead to the excited states Ψ italicn + 2(0) of H(0) with $n = 0,1,2, \cdots.$, thereby exhausting the full eigenspectrum of H(0). The workability of the proposed method is shown with several well‐known examples. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

The viability of noble gas axled boron nanowheels Ng M©B (Ng=Ar-Rn; M=Nb, Ta; n=1, 2) is explored by ab initio computations. In the resulting Ng -M complexes, the Ng-M-Ng nanorod passes through the center of the B ring, providing them with an inverse sandwich-like structure. While in the singly Ng bound analogue, the Ng binding enthalpy H at 298 K ranges from 2.5 to 10.6 kcal mol , in doubly Ng bound cases it becomes very low for the Ng M©B →Ng+NgM©B dissociation channel, except for the case of Rn, for which the corresponding H values are 3.4 (Nb) and 4.0 kcal mol (Ta). For a given Ng, Ta has slightly higher Ng-binding ability than Nb. The corresponding free-energy changes indicate that these systems, particularly the Xe and Rn complexes, are good candidates for experimental realization in a low-temperature matrix. The Ng-M bonds were found to be covalent in nature, as reflected in their large Wiberg bond indices, formation of a 2c-2e σ orbital between Ng and M centers in natural bond orbital and adaptive natural density partitioning (AdNDP) analyses, and the short Ng-M distances. Energy decomposition analysis and a study on the natural orbitals for chemical valence show that the Ng-M contact is supported mainly by the orbital and electrostatic interactions, with almost equal contributions. Although both the Ng→M σ donation and Ng←M π backdonation play roles in the origin of orbital interaction, the former is significantly dominant over the latter. Further, AdNDP analysis indicates that the doubly aromatic character (both σ and π) in MB clusters is not perturbed by the interaction with Ng atoms.