CCL: Energy minimization protocol for protein structures?

 Sent to CCL by: "Gerard  Pujadas" [gerard.pujadas,,]
 Dear CCL list subscribers,
 I wonder if there is any standard protocol to follow when doing an energy
 minimization of a protein structure.
 I would like to know also if there is a free (or low cost for non commercial or
 academic) and easy-to-use software that can do this kind of energy minimization
 With many thanks in advances.
 Yours sincerely,