Home › Forums › density functional theory › the Born-Oppenheimer approximation › Failure – Nucleui size This topic has 1 reply, 1 voice, and was last updated 12 hours, 23 minutes ago by monish. Viewing 2 posts - 1 through 2 (of 2 total) Author Posts November 5, 2025 at 1:30 pm #13915 monishParticipant I believe when nucleui is almost as small size as electron, this approximation with fail. November 5, 2025 at 1:39 pm #13916 monishParticipant After looking up fellow students’ answer, I believe BOA fails at high temperature when the nuclei are moving. Author Posts Viewing 2 posts - 1 through 2 (of 2 total) You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In