> if you actually do quantum chemistry I have—for my PhD dissertation I performed QMC calculations for lithium intercalation in carbon. Why do you assume I ha

> if you actually do quantum chemistry I have—for my PhD dissertation I performed QMC calculations for lithium intercalation in carbon. Why do you assume I haven't? > as the structure of DNA is defined partly by its environment (the specific details of waters that are only weakly bound... Yes. Of course I've done water box simulations. Should I elaborate on all the minutiae of molecular dynamics for the reader? Or am I allowed to make some simplifications? I'll be more precise: suppose we consider a strand of DNA and its immediate surrounding environment, and trace out the rest of the universe to produce a density matrix of just that subsystem. This is a solution to the Schrodinger equation for the entire subsystem, and we consider the resultant (not configurational) Hamiltonian for that system without any adiabatic approximations, making sure to specify a basis that removes symmetries (rotational, translational, permutational, etc.). Then you will find that if you could actually perform such a diagonalization of that massive Hamiltonian (I am quite aware that you can't), then a density plot of # eigenvalues vs energy will have peaks, and these peaks will correspond to real spatial structures of DNA, as previously mentioned. If you want to precisely specify "spacial structure", then let's use the definition of Salas, et al. (https://arxiv.org/pdf/2109.04542.pdf https://arxiv.org/pdf/2109.04542.pdf): > A generally unambiguous concept of shape is straightforward if we return to the original spatial probability density in (3N − 3)-dimensional configuration space. Maxima of this function will correspond to relatively likely configurations. We will refer to the arrangement of such maxima in the configuration space as the quantal shape of the system. Furthermore, I don't see how anything I said was particularly controversial, since I'm just paraphrasing others in the field. See R.F. Hendry in "Philosophy of Chemistry: Synthesis of a New Discipline", where he essentially says what I said above more precisely: The resultant Hamiltonian for any particular system is that which arises from the following method: i) Specify a list of fundamental physical interactions (gravitational, electormagnetic, strong- and weak-nuclear). ii) Enumerate the microparticles present in the relevant system and list their charges, masses, and values of any other relevant quantities. iii) Using only the approved “fundamental” forces in (i), list the interactions occuurring between the microparticles enumerated in (ii) iv) Using the results of steps (i)-(iii), write down the kinetic and potential energy operators and add them Happily for the strict physicalist, something very much like this method is taught to every student of quantum chemistry, with the proviso that particle enumeration remains at the level of electrons and nuclei, and only electrostatic terms are usually included in the potential energy operator. It really does yield a Hamiltonian for every molecule.