Q1. Derived from the tight-binding Hamiltonian of graphene, the band structure of graphene is composed by two branches: E+(kx,ky)=1s0f(kx,ky)0f(kx,ky)andE(kx,ky)=1+s0f(kx,ky)0f(kx,ky), where s0=0.129 and f(kx,ky)=1+4cos(23kxa)cos(2kya)+4cos2(2kya). Plot the band structure of graphene by matplotlib. 1. Define the dimensionless quantities: E~+=E+/0,E~=E/0,k~x=kxa and k~y=kya. Rewrite the above equations by E~+,E~,k~x and k~y. In the new equations, 0 and a are eliminated. So, we don't need to know the values of 0 and a. 2. Plot E~+(k~x,k~y) and E~(k~x,k~y) by plot_surface( ) in the same figure