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Hydrogen in a constant magnetic field

from vpython import *

scene.fullscreen = True

G = 10 # Coulomb constant in analogy to gravitational constant

# edit initial conditions here	 	 
##########
spheres = [
sphere(pos=vector(0,0,0),radius =6,color=color.red,charge=1000,mass=7200,velocity=vector(0,0,0),a = vector(0,0,0),trail=curve(color=color.red)),
sphere(pos=vector(0,100,-1),radius=2,color=color.blue,charge=-1,mass=1,velocity=vector(10,0,0),a=vector(0,0,0),trail=curve(color=color.blue)),
#sphere(pos=vector(0,12,0),radius=.08,color=color.green,mass=sqrt(4),velocity=vector(1.2,0,0.6),a=vector(0,0,0),trail=curve(color=color.green)),
#sphere(pos=vector(0,100,1),radius=2,color=color.white,charge=-1,mass=1,velocity=vector(-10,0,0),a=vector(0,0,0),trail=curve(color=color.white)),
#sphere(pos=vector(0,28,0),radius=.4,color=color.orange,mass=sqrt(80),velocity=vector(0.7,0,0.4),a=vector(0,0,0),trail=curve(color=color.orange)),
#sphere(pos=vector(0,32,0),radius=0.2,color=color.white,mass=-sqrt(10),velocity=vector(1.5,0,0.4),a=vector(0,0,0),trail=curve(color=color.white))
]

B=arrow(color=color.green,axis=vec(0,10,0))

def acceleration1on2(sphere2,sphere1):
    r = sphere2.pos - sphere1.pos
    r_mag = mag(r)
    normal_r = norm(r)
    g = ((G*sphere1.charge*sphere2.charge)/pow(r_mag,2))/sphere2.mass*normal_r
    return g
    
t = 0
dt = .5 # trade-off between simulation speed and numerical accuracy
while 1:
    rate(100)
    for i in spheres:
        i.a = vector(0,0,0)
        soi = vector(0,0,0)
        for j in spheres:
            if i!=j:
                i.a = i.a + acceleration1on2(i,j) 
                
    spheres[1].a += .001*cross(spheres[1].velocity, B.axis) # Lorentz force due to constant magnetic field           
                
    for i in spheres:
        i.velocity = i.velocity + i.a *dt
        i.pos = i.pos+i.velocity*dt
        i.trail.append(pos=i.pos)
                    
    scene.center=vector(spheres[0].pos.x,spheres[0].pos.y,spheres[0].pos.z)