enumeration for Restraint list potential types
Potential types are defined aS follows::
- log-harmonic:
Parameters: target_value, target_value_error
- parabolic:
Parameters: target_value, target_value_error
Formula: E = k(r-target_value)**2
- square-well-parabolic:
Parameters: upper_limit, lower_limit (optionally: target_value, target_value_error)
Formula:
E = k(r-upper_limit)**\2 for r > upper_limit
E = k(r-lower_limit)**2 for r < lower_limit
- 'square-well-parabolic-linear:
Parameters: upper_limit, lower_limit, upper_linear_limit, lower_linear_limit, (optional: target_value, target_value_error)
Formula:
If upper_limit = u, upper_linear_limit = u2, lower_limit = l, lower_linear_limit = l2:
E = 2k(u2-u)(r - (u2+u)/2) for r > u2
E = k(r-u)**2 for u < r < u2
E = k(r-l)**2 for l > r > l2
E = 2k(l2-l)(r - (l2+l)/2) for r < l2
Additional potential types
('upper-bound-parabolic', 'lower-bound-parabolic', 'upper-bound-parabolic-linear', 'lower-bound-parabolic-linear')
can be derived from the two-sided versions given above.