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    A permanent electric dipole moment (EDM) parallel to the atomic angular momentum can exist only if time-reversal symmetry T is violated by some interaction within atoms.
    Bond dipole moment
    Citations (0)
    The problem of the quantum-mechanical energy states of an electron in the field of a finite electric dipole is of great interest in several areas of physics and has been the subject of considerable study over a period of thirty years. It has been found that there is a minimum dipole moment required to produce binding of the electron. In view of the increase in the binding energy of the hydrogen atom in an external magnetic field, we have investigated the effect of a magnetic field on the binding by an electric dipole. Our results indicate that, unlike the zero-field case, the presence of a magnetic field always leads to binding. This situation is compared to the effect of a magnetic field on the binding of an electron by a neutral atom.
    Hydrogen atom
    Bond dipole moment
    Citations (7)
    Recently, anapole states as an interesting type of non-radiating sources attracted physicist's attention and have been insensitively studied. It was demonstrated that an electric dipole anapole state of a high permittivity dielectric particle is formed due to destructive interference between the radiation of electric dipole and electric toroidal moments. Here, we analytically study a magnetic anapole state with suppressed magnetic dipole radiation in a dielectric cylindrical particle. We demonstrate that this state is formed due to the destructive interference between magnetic dipole and magnetic toroidal dipole radiations in the far-field zone. We also investigate a three-fold hybrid anapole state which is obtained due to existence of electric dipole, magnetic dipole, and electric quadrupole anapoles at the same wavelength in a finite silicon nanodisk in optical domain.