Atom renderings are ridiculously too big

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The atom sizes that are rendered in the magnetic cell are HUGE. Given that a 
typical unit cell might have side lengths of 3, the atoms must be smaller.

In the AtomClass module, I tweaked the populateRadDict() method as follows. It 
basically simplifies the logic a bit and divides existing atoms' radii by 5. I 
see this as a temp fix but it might be useful to have the atoms have the 
properly proportioned radii with respect to each other, but all scaled down to 
fit the lattice. 

def populateRadDict():
    """This creates returns a dictionary containing all the keys in color_dict
    mapping to their default radii, which are the covalent_radii from periodictable."""
    default = 2; #default radius for elements whos radius is not included in periodictable

    radius_dict = {}
    for symbol in color_dict.keys():
        for element in periodictable.elements:
            if element.symbol == symbol:
                if element.covalent_radius:
                    radius_dict[symbol] = element.covalent_radius/5
                else:
                    radius_dict[symbol] = default                    
    return radius_dict

Original issue reported on code.google.com by wfly...@gmail.com on 16 Jul 2010 at 5:18