[en] Different computational procedures are compared for numerical solution of equations of motion for molecular dynamics of semi-rigid polymeric molecules with internal coordinates as general variables and an optimal method is proposed. The method uses forced conservation of momentum and angular momentum of the system and a predictor-corrector scheme with several iterations of correction for only generalized velocities at each time step. Variation of the accuracy of numerical solution with the time step and the order of the predictor-corrector algorithm is studied on three different partially fixed models of the oligopeptide (Ala)₉. The maximum possible time step gradually increases as fast degrees of freedom are frozen, For dynamics in torsion angles the method provides a reasonable accuracy for the time step as large as 0.02 ps. The difference between the results obtained here and the earlier estimates made by using Newtonian molecular dynamics with constraints is discussed. 28 refs., 6 figs., 1 tab