Potential, centrifugal electron-nuclear

Consider an JV-electron atom of nuclear charge Z, and let n,- = m,- - -1 denote the principle quantum number of the ith electron. A simple subhamiltonian may be constructed by boosting the centrifugal potential for each electron in Eq. (4) by the same factor used for a one-electron atom ... 

The vibration-rotation spectra and/or the rotational spectra in excited vibrational states provide the af constants and, when all the a/ constants are determined, the equilibrium rotational constants can be obtained by extrapolation. This method has often been hampered by anharmonic or harmonic resonance interactions in excited vibrational states, such as Fermi resonances arising from cubic and higher anharmonic force constants in the vibrational potential, or by Coriolis resonances. Equihbrium rotational constants have so far been determined only for a limited number of simple molecules. To be even more precise, one has further to consider the contributions of electrons to the moments of inertia, and to correct for the small effects of centrifugal distortion which arise from transformation of the original Hamiltonian to eliminate indeterminacy terms [11]. Higher-order time-independent effects such as the breakdown of the Bom-Oppenheimer separation between the electronic and nuclear motions have been discussed so far only for diatomic molecules [12]. 

Rotational constants, centrifugal distortion constants, rotation-vibration interaction constants, Dunham energy parameters, Dunham potential coefficients, parameters of the breakdown of the Bom-Oppenheimer approximation and of the nuclear field shift, and equilibrium intemuciear distances. Eiectronic spin-rotation, spin-spin, spin-orbit, and /1-doubling parameters and their centrifugai-distortion corrections in excited electronic states... 

The potential includes the Coulomb interaction, which has been written explicitly in terms of the effective nuclear charge. But it also includes a term that depends on the angular quantum number Z. This tells us that the effective potential in which the electron moves depends on the magnitude of its angular momentum. This observation is analogous to the centrifugal effect experienced by a macroscopic rotating body. 

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