FORCE CONCEPT FOR PREDICTING THE GEOMETRIES OF MOLECULES IN AN EXTERNAL ELECTRIC-FIELD

An intuitive Hellmann-Feynman (H-F) force concept is presented for pre dicting the geometries of molecules in external electric fields of var ious strengths. The field-induced H-F force consists of internal and e xternal forces and their balance determines the molecular geometry. Ou r previous model is valid in both strong and weak fields except for no n-protic hydrogens. This exception is explained to being due to the lo cal nature of the field-induced density reorganization, i.e. H-to-bond and bond-to-H electron flow, The force concept including this bond ef fect is applicable to various molecules in electric fields of various strengths. (C) 1998 Elsevier Science B.V. All rights reserved.