Separation of motions of atomic cores and valence electrons in molecules

Connecting a new non-adiabatic vibrational mass to the bonding mechanism of LiH: A quantum superposition of ionic and covalent states

“…Performing the calculations with a constant reduced mass averaged separately over each vibrational state (see [15,17,18]) yields practically the same results. Thus, the significant error reduction in the present calculations is solely due to the employment of the VBbased procedure for calculating the effective reduced mass.…”

“…The first is the density that moves along with the first nucleus when the molecule vibrates, the second part moves with the second nucleus, and the The moving parts were called core and the stationary part was called valence. A procedure based on the Mulliken population analysis was developed to determine the electronic masses of the core parts and of the valence part for simple homonuclear diatomics [15,17] and for H + 3 [18]. These applications produced R-dependent reduced masses, which, when used in the vibrational equation, resulted in a significant improvement of the results.…”

“…Moreover, making the reduced mass independent on R, but replacing the nuclear masses by the atomic mass, as done in [11], was found to give better results. Mohallem et al [15] showed that the electron density in a diatomic molecule can be separated into three parts. The first is the density that moves along with the first nucleus when the molecule vibrates, the second part moves with the second nucleus, and the The moving parts were called core and the stationary part was called valence.…”

“…An alternative approach to account for non-adiabatic effects is based on the realization that the source of these effects is due to a part of the electronic cloud moving with the nuclei when they vibrate or rotate [13][14][15]. This also leads to the concept of an effective coordinate-dependent reduced mass (R), which is connected to the perturbative second-and third-order nonadiabatic corrections [14].…”

Spectroscopy of H 3 + based on a new high-accuracy global potential energy surface

“…We were able to achieve highly accurate results of ro-vibrational level calculations using the simple model by Polyansky & Tennyson [10], namely using constant (though different) vibrational and rotational masses. Clearly, further improvement in the accuracy of nonadiabatic calculations requires more sophisticated models, as the example of the H 2 molecule shows [68][69][70][71].…”