http://localhost:80/xmlui/handle/123456789/1081 2026-04-05T17:20:36Z 2026-04-05T17:20:36Z Ghosh, Sourav Ranjan Halder, Sasthi Charan Jana, Atish Dipankar http://localhost:80/xmlui/handle/123456789/10793 2026-04-01T07:33:14Z 2025-04-01T00:00:00Z

Title: Evolution of B13n (n = + 3 to − 3) wheel with electron injection/abstraction: an insight from electronic structure analysis Authors: Ghosh, Sourav Ranjan; Halder, Sasthi Charan; Jana, Atish Dipankar Abstract: The planar B13+1 cluster, a prototypical molecular ‘Wankel motor’, has captivated the scientific community with its exceptional stability as well as rotor action. The present study is an exploration of how incremental electron injection/abstraction influences the electronic structure of B13 clusters with B13+1 as a reference one. It has been found that seven different charge states (from + 3 to − 3) of B13 cluster are possible, among which B13−1 triplet is the lowest energy cluster. For B13n clusters, n =  + 3 to − 2, the clusters are planar and possess C2v symmetry and their relative atomic arrangement is similar to B13+1 ground state (GS) structure in which a triangular boron core is encircled by ten peripheral boron atoms. B13−3 cluster has a different geometric arrangement of atoms like that of the B13+1 transition state (TS) structure; remains planar, possesses C2v symmetry. The different atomic arrangement of B13−3 can be assigned to the electronic structural relaxation to reduce the electronic stress arising from high negative charge. B13+1 cluster is characterized by a unique electron density distribution in the cluster plane which is analogous to a ‘tri-spoke wheel’ configuration. In it, three spokes of electron dense lines connect the triangular core to the nearly circular periphery. The present study unveils how the injection or abstraction of electrons modifies the electronic topology in the cluster plane and how the spoke-wheel geometry evolves. It has been found that, in the + 3 and + 2 charge states, the wheel consists of four and five spokes respectively. On the other hand, for all other clusters, the overall electronic topology resembles that of the tri-spoke wheel-like B13+1 cluster. AIM analysis helped to trace out and characterize the evolution of the spoke-wheel topology with electron density at ring critical points and the bond paths.

2025-04-01T00:00:00Z Chakraborty, A. http://localhost:80/xmlui/handle/123456789/10792 2026-04-01T07:32:57Z 2025-01-01T00:00:00Z

Title: Bi-orthogonal quantum mechanics related to T -pseudo- Hermitian Rashba Hamiltonian. Authors: Chakraborty, A. Abstract: A non-Hermitian version of Rashba Hamiltonian has been introduced. The said Hamiltonian is found to be pseudo-Hermitian under fermionic time-reversal and its eigen-states show a kind of two-parameter-bi-orthogonality. The possibility of an equivalent version of Kramers’ degeneracy theorem has been explored and the supersymmetric and pseudo-supersymmetric structures relating to the present system are also discussed. Description: 10.1088/1402-4896/add391

2025-01-01T00:00:00Z Lakshan, Achintya Koley, Biplab Buxi, Krishnendu Raghuvanshi, Parul R. Nuss, Jürgen Bhattacharya, Amrita Chatterjee, Ritayan Roy, Ahin Jana, Partha Pratim http://localhost:80/xmlui/handle/123456789/10791 2026-04-01T07:32:41Z 2024-01-01T00:00:00Z

Title: Disorder-Mediated Structural Transformation in the Cu4TiSe4–xSx (0 ≤ x ≤ 4) System and Its Effects on the Thermal Transport Property Authors: Lakshan, Achintya; Koley, Biplab; Buxi, Krishnendu; Raghuvanshi, Parul R.; Nuss, Jürgen; Bhattacharya, Amrita; Chatterjee, Ritayan; Roy, Ahin; Jana, Partha Pratim Abstract: Copper-transition-metal chalcogenides can offer low-cost and environmentally benign solutions to trap heat and heat to electric energy conversion. In this report, we present the synthesis and characterization of Cu–Ti-based mixed chalcogenides, Cu4TiSe4–xSx (x = 0–4). At room temperature, Cu4TiSe4 adopts a sulvanite-type cubic structure (P4̅3m), whereas Cu4TiS4 crystallizes in a body-centered tetragonal space group (I4̅2m), where the lattice parameter is doubled along the c-direction w.r.t. the sulvanite. The structure of the S-analogue is completely ordered, while the Se-analogue hosts positional disorder distributed over two Cu-sites (1a and 4e Wyckoff sites). A systematic investigation of a series of compositions of Cu4TiSe4–xSx (0 ≤ x ≤ 4) indicates that S insertion in the Cu4TiSe4–xSx boosts the disordered 4e site to coalesce into the 1a site. Up to x ≈ 2.6, Cu4TiSe4–xSx forms the cubic phase similar to Cu4TiSe4, whereas, for x ≥ 3.5, the pure tetragonal phase related to Cu4TiS4 appears. Herein, the cubic-to-tetragonal phase transformation is rationalized by theoretical calculations. Thermal conductivity measurements show a significant increase in the lattice thermal conductivity (κL) values from the cubic (0.3–0.47 Wm–1 K–1) to the tetragonal (above 0.7 Wm–1 K–1) phases. Phonon band structure and phonon density of state calculations suggest that both Cu and Se atoms are responsible for the anharmonic scattering of the acoustic phonons in the Se-rich cubic phase, whereas Cu atoms primarily contribute to this scattering process in the S-rich tetragonal phase. Description: https://pubs.acs.org/doi/10.1021/acs.chemmater.4c00904.

2024-01-01T00:00:00Z Chakraborty, Arindam http://localhost:80/xmlui/handle/123456789/10790 2026-04-01T07:32:28Z 2024-01-01T00:00:00Z

Title: On Some novel features of a Non-Hermitian multi-boson Hamiltonian : partial PL -symmetry and ghosts Authors: Chakraborty, Arindam Abstract: The eigenvalues and eigenstates of a three-boson Hamiltonian are considered. The Hamiltonian is found to be pseudo-Hermitian in relation to its various partial PT-symmetries understood in a Fock space setting. The possibilities of symmetry adopting and symmetry breaking states are also discussed. Ghost states are found in relation to different symmetry induced inner-products. At least two of the ghost states show some kind of transition to normal states depending on the values of certain parameter. Description: 10.1088/1402-4896/ad8fdc

2024-01-01T00:00:00Z