density functional theory band structure calculation

#Density functional theory band structure calculation full
#Density functional theory band structure calculation software

The calculation for (c) and (d) is carried out with 4 × 6 unit cells the dielectric constant is chosen to be 15 the distance between gate and sample is chosen to be d = 300 Å the twist angle is 3.89°. During the flux insertion, the many-body gap is maintained. (d) The evolution of ground states under flux insertion along the k 2 direction.

#Density functional theory band structure calculation full

(c) The many-body spectrum as a function of total crystalline momentum with the assumption of full valley polarization at ν = − 2 / 3. Band structures obtained from density-functional theory calculations within generalized-gradient approximation (GGA) (top) and using the GGA U method with. The calculation for (b) is carried out with 3 × 4 unit cells. The energy difference between the lowest state with spin flip(s) and the ground state is defined as the spin gap, shown in (b) for ν = − 1 / 3 and ν = − 2 / 3 as a function of the twist angle. The bottom of (a) shows an example of the excited state with one spin flip. The arrows represent spin, which is locked to the valley ( K and K ′) degree of freedom. Our research highlights the importance of accurate single-particle band structure in the quest for strong correlated electronic states and provides insights into engineering fractional Chern insulator in moiré superlattices.įor a large range of twist angles, the ground state of twisted bilayer MoTe 2 is fully valley polarized, as shown in the top of (a). We further demonstrate that an external electric field can destroy the FCI state by changing band geometry and show evidence of the ν = − 3 / 5 FCI state in this system. We establish phase diagrams with respect to the twist angle and electron interaction, which reveal an optimal twist angle of 3.5° for the observation of FCI. The existence of the FCI state at ν = − 2 / 3 is confirmed by exact diagonalization. In this Letter, we perform large-scale density functional theory calculation for the twisted bilayer MoTe 2 and find that lattice reconstruction is crucial for the appearance of an isolated flat Chern band. The experimental observation is at an unexpected large twist angle 3.7° and calls for a better understanding of the FCI in real materials. A complex band structure describes the dispersion relation not only of propagating bulk states but also of evanescent ones, both of which are together referred to as generalized Bloch states and are important for understanding the electronic nature of solid surfaces and interfaces.

#Density functional theory band structure calculation software

We validate our software by calculating the energy band structure of Silica, Carbon, and.

A recent experiment has reported the first observation of a zero-field fractional Chern insulator (FCI) phase in twisted bilayer MoTe 2 moiré superlattices. This will facilitate the scientific community to develop the software.