I'd like to ask a couple of questions. As a solid object gets bigger, the molecular orbital (combinations of all single atom orbitals) has greater size too? For a one inch square object (of closely packed molecules like crystals), what is its molecular orbital size compared to a one foot square crystal object? Second. When photons hit an object and the molecules. They are absorbed as molecular vibrations and redistribution into normal modes. The molecular orbital is not affected because you need much higher energy photons to affect the electronic orbitals. So what is the connection of molecular orbital to molecular vibrations?