Electronic and lattice dynamics properties of one-dimensional chain of NbSe

Theoretical investigations of the electronic properties and lattice thermal properties of a one-dimensional chain of transition metal trichalcogenide, $\mathrm {NbSe}_{3}$ , are performed using first-principles calculations based on density functional theory (DFT). Although the system remains metallic even in the one-dimensional chain, an indirect band gap between the valence band maxima and the conduction band minima opens up, and a band inversion can be seen at the Γ-point with and without the inclusion of spin-orbit coupling (SOC) due to the lattice distortion in the 1D-chain. Moreover, the finite value of anisotropic displacement parameter (ADP) is discussed in the context of Mermin-Wagner theory. ADP values indicate that, unlike in bulk, the chemical bond strength is not equal in a 1D-chain. Lattice dynamics calculations show four acoustic phonon modes for a pure one-dimensional system and eight Raman active modes. The lattice-specific heat capacity is linearly dependent on temperature (T) for the 1D case, whereas it follows T3 for the 3D-$\mathrm {NbSe}_{3}$ case. These calculations suggest that the 1D-chain of $\mathrm {NbSe}_{3}$ is a stable structure with promising electronic and thermal properties, and further experimental investigation is required for its application in nano-electronics and other devices.