Gear formalism of the always stable predictor-corrector method for molecular dynamics of polarizable molecules.

The recently proposed always stable predictor-corrector method for molecular dynamics of polarizable molecules [J. Kolafa, J. Comput. Chem. 25, 335 (2004)] is rewritten in the Gear formalism. This equivalent form simplifies an implementation if the Newton equations of motion are integrated by the Gear method and also enables a variable integration step. Algorithms are presented for both the original and new versions and tested on a pair of polarizable ions exhibiting anharmonic vibrations.