bit cleaned up, bit other B

from vpython import *

G = 100 #prefactor electric force, code adapted from gravity sim therefore 'G'

B=vector(0,1,1) #constant overall manetic field, should be enough to introduce chaos to 2 particle system (later I'd like to have it caused by the nuclear spin and affect the electron spin, all classical of course)
# cp. https://arxiv.org/abs/chao-dyn/9601009
# Lorentz force is q*cross(v,B), here: charge*cross(velocity,B)

# edit initial conditions here       
##########
spheres = [
sphere(pos=vector(2,0,0),radius =.1,color=color.blue,charge=-1,mass=1,velocity=vector(0,-5,0),a = vector(0,0,0)),
#sphere(pos=vector(0,0,0),radius=.3,color=color.red,charge=1,mass=7200,velocity=vector(0,0,0),a=vector(0,0,0)),
#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(0,0,0),radius=.3,color=color.red,charge=1,mass=7200,velocity=vector(0,0,0),a=vector(0,0,0))
#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))
]

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 = .01
while 1:
    rate(60)
    for i in spheres:
        i.a = vector(0,0,0)
        for j in spheres:
            if i!=j:
                i.a = i.a + acceleration1on2(i,j)


    # only for electron Lorentz force, assume nucleus resting in field (should later be caused by it)
    # spheres[0].charge*cross(spheres[0].velocity,B)
    lorentz_acc = spheres[0].charge*cross(spheres[0].velocity,B)/spheres[0].mass #acceleration due to B on e-
    spheres[0].a += lorentz_acc          


    for i in spheres:
        i.velocity = i.velocity + i.a *dt
        i.pos = i.pos+i.velocity*dt