Eckart conditions

The Eckart conditions are a set of criteria in the context of molecular mechanics and computational chemistry. They are primarily associated with the study of molecular vibrations and the construction of force fields for molecular simulations. The conditions are formulated to ensure that the parameters used in molecular models are physically meaningful and to eliminate non-physical modes that could arise in the computation of molecular forces. More specifically, the Eckart conditions address the issue of removing the translational and rotational motions from the vibrational analysis of a molecule.