Hi Siesta Users. This question is basic but due to my stupidity I could not answer it. Below is my question: First, take a look on this following page. This is octopus pseudopotential generation for Hydrogen atom ----- Input http://www.tddft.org/programs/octopus/pseudo.php Output http://www.tddft.org/programs/octopus/pseudo_cat.php?d=PPm88Fks&f=2 ----- Scroll down of output page until you got the total energy of Hydrogen. total energies --------------
sum of eigenvalues = -0.46732456 kinetic energy from ek = 0.82349817 el-ion interaction energy = -1.81488127 el-el interaction energy = 0.56444567 vxc correction = -0.60483292 virial correction = 0.04206809 exchange + corr energy = -0.46414171 kinetic energy from ev = 0.82349830 potential energy = -1.71457732 --------------------------------------------- total energy = -0.89107902 This case it's equal to -0.89107902 Rydberg (or -12.12 eV). Compared it to the standard value from NIST site (http://physics.nist.gov/PhysRefData/DFTdata/Tables/01H-T.html) ----------- 1 H 1s (Energy in hartree) LDA LSD RLDA ScRLDA Etot = -0.445671 -0.478671 -0.445668 -0.445668 Ekin = 0.425027 0.466643 0.425020 0.425020 Ecoul = 0.282827 0.298377 0.282824 0.282824 Eenuc = -0.920999 -0.965619 -0.920997 -0.920996 Exc = -0.232525 -0.278072 -0.232516 -0.232515 1s -0.233471 -0.268975 -0.233463 -0.233463 -------- We see the total energy of Hydrogen atom is approximate -12.12 eV. This total energy is quite different with the experimental value of Hydrogen which is equal to -13.6 eV. I believe that the NIST standard value could not be wrong so the result generated by Octopus or any pseudopotential generator is reliable but I find that I could not understand why there is such that difference between the calculated and experimental value. Or I am missing something. Hope anyone clear this basic question. Thanks, Sau Nguyen U of Houston
