bohr = 4.0 * pi * epsilon_0 * hbar**2 / (electron_mass * elementary_charge**2) = a0
atomic_time = hbar / hartree = t0
kcalpermol = kcal / 6.0221412927e23
kjpermol = kJ / 6.0221412927e23
gpermol = g / 6.0221412927e23
debye = 0.393430307 * elementary_charge * bohr
electron_charge = elementary_charge
q_e = elementary_charge

@system nano using international
   nanometers
   nanoseconds
   atomic_mass_units
@end

