Abstract
Use of the London‐Eyring‐Polanyi + 3‐Center + power‐series (LEP‐3C‐PS) analytical potential as a fit to potential energy surfaces (PES) which are known numerically only are suggested. This analytical fit was performed for the diatomics‐in‐molecules + 3 Center (DIM‐3C) PES of HCl2 and HI2 systems. The HCl2 analytical LEP‐3C‐PS potential was used for classical trajectory calculations of the Cl' + HCl → HCl' + Cl reaction. The rate constant obtained from these calculations for T = 358° K is 1.95 X 109 cm3/mol sec which is close to the experimental value of 2.5 109 cm3/mol sec.