why system has a rotational symmetry in dirac equation?
is that a general property of all systems?
Because Dirac equation was initially applied to free-electrons and an electron in hydrogen atom. Space of constant potential and that containing only one atom (generally multiple electron) must have rotational symmetry. If, however, you want to extend Dirac equation to diatomic molecules, rotational symmetry does not apply.
Thank you so much. it's really helpful!
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