Lagrange multipliers energy surfaces

Manaa MR, Yarkony DR (1993) On the intersection of two potential energy surfaces of the same symmetry. Systematic characterization using a lagrange multiplier constrained procedure. J Chem Phys 99 5251... 

Yarkony, D. R. (1993). Systematic determination of intersections of potential energy surfaces using a Lagrange multiplier constrained procedure. Journal of Physical Chemistry, 97(17), 4407-4412. 

The mathematical problem of locating a minimum on the seam between two energy surfaces is a constrained optimization, i.e., the energy should be minimized subject to the constraint that the reactant and product energies are equal. This may be handled, for example, by the technique of Lagrange undetermined multipliers, and optimization of the Lagrange function may be done by NR techniques ... 

Potential Energy Surfaces of the Same Symmetry. Systematic Characterization Using a Lagrange Multiplier Constrained Procedure. 

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