First derivatives of the total energy with respect to nuclear coordinates, i.e
., negative values of forces on the nuclei. Evaluation of energy gradient
plays a central role in searching potential energy surfaces for stationary points.
A widespread technique is based on the minimization of the gradient
norm (the square of energy gradient
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. https://doi.org/10.1351/goldbook