Results

Minimum energy calculated by this method is always lower than the correct energy:

At the minimum,

$$\displaystyle{\frac{\partial Q}{\partial f_i} = 0 = \frac{\pa... ...l E}{\partial f_i} -2\lambda + \frac{\partial P}{\partial f_i}}$$

• Accurate correction
• Analytic form

$\Rightarrow$ take derivatives to obtain forces.