Max Born & Robert Oppenheimer, Zur Quantentheorie der Molekeln [On the Quantum Theory of Molecules]. Leipzig: 1927. 1st edition. Published in the Annalen der Physik, IV/ vol 84, in 1927. Bound in the 1950's in a good, sturdy, black cloth. Fine condition, with a few unobstrusive internal library marks of ownership (and deaccession). We offer the entire volume of 1062pp, the Born-Oppenheimer Approximation occupying pp 457-484. $225.00
From WIKI: "In quantum chemistry, the computation of the energy and wavefunction of an average-size molecule is a formidable task that is alleviated by the Born-Oppenheimer (BO) approximation. For instance the benzene molecule consists of 12 nuclei and 42 electrons. The time independent Schroedinger equation, which must be solved to obtain the energy and molecular wavefunction of this molecule, is a partial differential eigenvalue equation in 162 variables the spatial coordinates of the electrons and the nuclei. The BO approximation makes it possible to compute the wavefunction in two less formidable, consecutive steps. This approximation was proposed in the early days of quantum mechanics by Born and Oppenheimer (1927) and is still indispensable in quantum chemistry.