Hello, I'm studying a type of chemical structures with intramolecular hydrogen bonds using gaussian09. I optimized the geometry of the said structures with M062X 6-31+g(d), and they seem to display strong hydrogen bonds (based of the distances). I want to complement this with the stabilization energies E(2) from Second Order Perturbation Theory in Natural Bond Orbital population analysis. From what I understand I should have a line in the output similar to LP ( 1) O a /***. BD*( 1) O b - H c (considering a hydrogen bond between two carboxyl groups) corresponding to the interaction nOa -> σ*Ob-Hc, however, I can't find any line with BD*( 1) O - H in the output files. I then found the lines LP ( 1) O a /***. LP*( 1) H c, that seem to have the E(2) values I should be expecting, what does this mean? Can somebody help please?