Field-driven electronic and topological modulation in the Weyl semimetal NbP

The Weyl semimetal NbP exhibits remarkable electronic properties arising from its nontrivial topology and symmetry-protected nodes. Here, we explore how tensile strain and external electric fields can modulate its electronic bands and topological characteristics using first-principles density functional theory combined with model Hamiltonian approaches. All calculations are performed within the plane-wave pseudopotential framework, including spin-orbit coupling, and maximally localized Wannier functions are employed to analyze the Berry curvature, Fermi arcs, and node evolution. Under a 4% tensile strain, NbP develops a small band gap of ∼0.05 eV along the Γ-Σ direction, accompanied by a reduction in carrier density near the Fermi energy. Increasing strain to 8% leads to a gap of ∼0.035 eV and further suppression of Fermi-level states, indicating strain-driven band reorganization. The application of electric fields produces minute but significant effects: at 0.51 V Å^-1, band curvature shifts slightly, while at 1.29 V Å^-1, a gap of ∼0.02 eV opens along the Γ-Spath. This controlled gap opening signifies a transition toward switchable electronic phases, highlighting NbP's potential in topological electronics and field-tunable quantum devices.