a=30
import math
ratio=(1-math.cos(a*math.pi/180.0))/math.cos(a*math.pi/180.0)
print"Cation to anion raio is ",round(ratio,3)
r_Fe=0.077 # in nm Radius of iron cation Fe++
r_O=0.140 #in nm Radius of Oxygen anion O--
ratio=r_Fe/r_O
print"Ratio is ",ratio
if 0.414<ratio<0.732:
print"Co-ordinaton no. is 6"
print"Structure is Rock Salt type"
else:
print "Coordination no is not 6"
A_Na=22.99 # in g/mol
A_Cl=35.45 #in g/mol
r_Na=0.102*10**-7 #in cm Radius of Na+ ion
r_Cl=0.181*10**-7 #in cm Radius of Cl- ion
Na=6.023*10**23 #Avogadro number
a=2*(r_Na+r_Cl)
V=a**3
n=4 #For FCC, no. of atoms are 4 per crystal
density=n*(A_Na+A_Cl)/(V*Na)
print"Density is ",round(density,2),"gm/cm**3"
Na=6.023*10**23 #Avogadro number
density=1.955 #in g/cm**3
A_K=39.1 #in g/mol
A_Cl=35.45 #in g/mol
import math
N=Na*density*10**6/(A_K+A_Cl)
Qs=2.6 # in eV
k=8.62*10**-5 # in eV/K Boltzmann Constant
T=500.0+273.0 # in K
Ns=N*math.exp(-Qs/(2*k*T))
print"No. of Schottky Defects are ",round(Ns,-17),"/m**3"