[Uso de matplotlib y numpy] Potencial de Morse

##POTENCIAL DE MORSE BY FORTIL##

import numpy as np
import matplotlib.pyplot as plt

def rango(x,x1):
    return np.arange(x,x1,0.1)

def f(x,v0):
    return v0*(1-x)**2

def ex(x, a=0.5, x0 = 2.0, v0 = 0.05):
    return f(np.exp(-a*((x)-x0)),v0)

def coseno(x,a):
    return a+0.0005*np.cos(10*x+np.pi)
    
x = np.arange(0, 80.0, 0.1)

fig = plt.figure()
ax1 = fig.add_subplot(111)

ax1.plot(x, ex(x), 'b-',x,ex(x,0.05),'r-')
ax1.set_title("Potencial de Morse por Fortil", fontsize=16)
ax1.set_ylabel(r'$V_f$')
ax1.set_xlabel(r'$X$')

ax1.text(20,0.025,r"$\alpha_1 $ mayor",fontsize=12, color='r')
ax1.text(7,0.035, r"$\alpha_2 $ menor", fontsize=12, color='b')
ax1.text(60,0.051, r"$V_0 = 0.05$", fontsize=12, color='y')
ax1.text(60,0.009, r"$X_0 = 2.0$", fontsize=12, color='black')
ax1.text(20,0.06,r"$\alpha_2 = \frac{\alpha_1}{10} $",
         fontsize=14, color='g')
ax1.text(25,0.12,r"$V_f = V_0\times[1-e^{-\alpha(X-X_0)}]$",
         fontsize=18, color='black')

ax1.plot(rango(ex(0.6),80.0),
         coseno(rango(ex(0.6),80.0),0.05),'c-')
ax1.acorr(x, usevlines=False, normed=True, maxlags=1, lw=2)
ax1.set_ylim(0,0.16)
ax1.set_xlim(0,70)

plt.show()