Graphene band structure

This example plots the band structure of graphene, a 2D material. 2D band structures are not supported natively (yet), so we manually build a custom path in reciprocal space.

using DFTK
using LinearAlgebra
using Plots
using PseudoPotentialData
using Unitful
using UnitfulAtomic

# Define the convergence parameters (these should be increased in production)
L = 20  # height of the simulation box
kgrid = [6, 6, 1]
Ecut = 15
temperature = 1e-3

# Define the geometry and pseudopotential
a = 4.66  # lattice constant
a1 = a*[1/2,-sqrt(3)/2, 0]
a2 = a*[1/2, sqrt(3)/2, 0]
a3 = L*[0  , 0        , 1]
lattice = [a1 a2 a3]
C1 = [1/3,-1/3,0.0]  # in reduced coordinates
C2 = -C1
positions = [C1, C2]
C = ElementPsp(:C, PseudoFamily("cp2k.nc.sr.pbe.v0_1.semicore.gth"))
atoms = [C, C]

# Run SCF
model = model_DFT(lattice, atoms, positions; functionals=PBE(), temperature)
basis = PlaneWaveBasis(model; Ecut, kgrid)
scfres = self_consistent_field(basis)

# Construct 2D path through Brillouin zone
kpath = irrfbz_path(model; dim=2, space_group_number=13)  # graphene space group number
bands = compute_bands(scfres, kpath; kline_density=20)
plot_bandstructure(bands)