Hey there. I'm trying to redo basic quantum chemistry with a lot more rigor. I'm currently using Pauling's "Introduction to Quantum Mechanics With Applications to Chemistry". Here is a copy of the page(s) I will be referring to: http://books.google.com/books?id=vd...X&oi=book_result&resnum=5&ct=result#PPA113,M1 I'm getting caught up in the basic details. So... I have a few questions for the experts. 1. The potential energy operator is defined as -Ze^2/r. Excuse my stupidity, but why was the factor of k (1 / 4*pi*epsilon) left out? It seems like the rest of the equation is in SI. 2. The Schrodinger equation can be separated into the product of a wavefunction which deals with the translational motion of the atom, and another wavefunction which describes the interaction between the proton and electron.... It makes sense to me to let x,y, and z equal the center of mass of the system. I'm a little confused as to why the "relative" x,y, and z coordinates are used for the substitution in spherical coordinates. Rather... I don't understand the consequences of such substitutions. You can't really interpret the system graphically in terms of the usual r/theta/phi, because they don't have their usual meaning in this case. The rest is just calculus which I can definitely handle :) Any help would be appreciated.