First-Principles Study Of Pressure-Induced Topological Evolution In Doped Bi₂Se₃ Using Density Functional Theory And Wannier-Based Methods

Abstract

In this study, we employ density functional theory (DFT) calculations to investigate the structural, electronic, and topological evolution of Nb-doped Bi₂Se₃ under varying hydrostatic pressures. Bi₂Se₃ is a well-established three-dimensional topological insulator characterized by a bulk band gap and protected Dirac-like surface states. Doping and pressure are two key parameters for modulating its topological features, yet their combined effects remain incompletely understood.Using VASP and Wannier-based tools, we simulate the pressure-dependent band structure, density of states, and surface spectral functions. Our findings reveal a pressure-induced topological phase transition, confirmed by the inversion of bulk bands and the evolution of the Z₂ invariant. The emergence and robustness of topological surface states are preserved across moderate pressure regimes, while higher pressures lead to gap closure and possible transition to a trivial insulator phase. Nb-doping further modulates the Fermi level and enhances orbital hybridization, offering additional tunability of electronic properties.This work highlights the potential of pressure and doping as complementary tuning knobs for controlling topological phases in Bi₂Se₃, contributing to the design of tunable topological devices and quantum materials.