Model I-V in Python

Model I-V.

Method: Perform an integral, as a function of E, which outputs Current for each Voltage value used. This is repeated for an array of v_values. The equation can be found below.

Although the limits in this equation range from -inf to inf, the limits must be restricted so that (E+eV)^2-\Delta^2>0 and E^2-\Delta^2>0, to avoid poles. (\Delta_1 = \Delta_2). Therefore there are currently two integrals, with limits from -inf to -gap-e*v and gap to inf.

However, I keep returning a math range error although I believe I have excluded the troublesome E values by using the limits stated above. Pastie of errors: http://pastie.org/private/o3ugxtxai8zbktyxtxuvg

Apologies for the vagueness of this question. But, can anybody see obvious mistakes or code misuse?

My attempt:

from scipy import integrate
from numpy import *
import scipy as sp
import pylab as pl
import numpy as np
import math

e = 1.60217646*10**(-19)
r = 3000
gap = 400*10**(-6)*e
g = (gap)**2
t = 0.02
k = 1.3806503*10**(-23)
kt = k*t

v_values = np.arange(0,0.001,0.0001)

I=[]
for v in v_values:
    val, err = integrate.quad(lambda E:(1/(e*r))*(abs(E)/np.sqrt(abs(E**2-g)))*(abs(E+e*v)/(np.sqrt(abs((E+e*v)**2-g))))*((1/(1+math.exp((E+e*v)/kt)))-(1/(1+math.exp(E/k*t)))),-inf,(-gap-e*v)*0.9)
    I.append(val)
I = array(I)

I2=[]
for v in v_values:
    val2, err = integrate.quad(lambda E:(1/(e*r))*(abs(E)/np.sqrt(abs(E**2-g)))*(abs(E+e*v)/(np.sqrt(abs((E+e*v)**2-g))))*((1/(1+math.exp((E+e*v)/kt)))-(1/(1+math.exp(E/k*t)))),gap*0.9,inf)
    I2.append(val2)
I2 = array(I2)

I[np.isnan(I)] = 0
I[np.isnan(I2)] = 0

pl.plot(v_values,I,'-b',v_values,I2,'-b')
pl.show()

The best way to approach this problem in the end was to use a heaviside function to preventE variable from exceeding \Delta variable.