The EckartÂ–Watson form of this operator is useful in the context of bent triatomic molecules, though it becomes singular for linear molecules.
The EckartÂ–Watson form of this operator is useful in the context of bent triatomic molecules, though it becomes singular for linear molecules. The Hellman-Feynmann theorem applies when this operator depends continuously on a parameter, and the time derivative of some operator depends on its commutator with this operator according to the Ehrenfest theorem.  This operator is the generator of the the time evolution operator, so this operator's eigenfunctions are stationary states.  The time-dependent Schrodinger equation states the time derivative of the wave function is proportional to this operator acting on the wave function.  FTP, name this function equal to the sum of kinetic and potential energy, and named after an Irish mathematician.
The EckartÂ–Watson form of this operator is useful in the context of bent triatomic molecules, though it becomes singular for linear molecules.
hamiltonian [prompt on "H," prompt on "Energy"]