## Calculate energy difference
import math
n_x1 = 1. ## atomic level
n_y1 = 1.## atomic level
n_z1 = 1.## atomic level
n_x2 = 2.## atomic level
L = 10. ## lattice parameter in mm
h = 6.626e-34 ## plank constant
m_e = 9.109e-31 ## mass of electron in kg
print("\n Example 14.1")
E1 = h**2.*(n_x1**2.+n_y1**2.+n_z1**2.)/(8.*m_e*(L*1e-3)**2.)
E2 = h**2.*(n_x2**2+n_y1**2.+n_z1**2.)/(8.*m_e*(L*1e-3)**2.)
E = E2-E1 ## energy difference
print'%s %.2e %s '%("\n Energy difference is ",E," J ")
## Calculate conductivity of copper at 300 K
import math
tau = 2e-14 ## collision time of electron in s
e = 1.602e-19 ## charge on electron
m_e = 9.1e-31 ## mass of electron in kg
print("\n Example 14.2")
n = 6.023e23*8960/0.06354
sigma= n*e**2*tau/m_e
print'%s %.2e %s '%("\n Conductivity of copper at 300 K is ",sigma," ohm^-1 m^-1 ")
## Estimation of resistivity due to impurity scattering of 1% of Nickel in copper lattice
import math
r_cu = 1.8e-8 ## resistivity of pure copper in ohm-m
r_Ni_cu = 7e-8 ##resistivity of copper 4% Ni in ohm-m
per1 = 4.##impurity in percent
per2 = 1. ## impurity in percent
print("\n Example 14.3")
r = (r_Ni_cu-r_cu)*per2/per1 ## resistivity of copper 1% Ni in ohm-m
print'%s %.2e %s '%("\n Resistivity due to impurity scattering of 1 %% of Nickel in copper lattice is ",r," ohm-m")