Energy bond lengths and ionization

A systematic study of the first ionization potentials of Zn clusters as a function of cluster size with up to 43 atoms reveals that at least 20 transition metals are needed to approach surface (bulk) electronic structure properties. In addition, for the first time LSDF theory predicts a stable Zn dimer with a realistic bond length and binding energy. 

There are many reports concerning metal clusters in a variety of fields such as physics, chemistry, and engineering (1-3). The metal clusters are found to exhibit some properties which are different from those of the bulk material, for example bond length (4), ionization energy (I), magnetic moment (5), and so on. One of the most interesting features of the metal clusters is their geometrical structure which is often different from the bulk structure. 

Figure 8. Relationship between the bond length, and the energy difference between the g resonance and the ionization potential (IP). Z = sum of the atomic numbers of the bonded pair. [Used with permission of Springer-Verlag from Stohr (1991), Fig 8.6, p. 250.]...

Unlike the stable molecule N2O, the sulfur analogue N2S decomposes above 160 K. In the vapour phase N2S has been detected by high-resolution mass spectrometry. The IR spectrum is dominated by a very strong band at 2040 cm [v(NN)]. The first ionization potential has been determined by photoelectron spectroscopy to be 10.6 eV. " These data indicate that N2S resembles diazomethane, CH2N2, rather than N2O. It decomposes to give N2 and diatomic sulfur, S2, and, hence, elemental sulfur, rather than monoatomic sulfur. Ab initio molecular orbital calculations of bond lengths and bond energies for linear N2S indicate that the resonance structure N =N -S is dominant. 

The active space used for both systems in these calculations is sufficiently large to incorporate important core-core, core-valence, and valence-valence electron correlation, and hence should be capable of providing a reliable estimate of Wj- In addition to the P,T-odd interaction constant Wd, we also compute ground to excited state transition energies, the ionization potential, dipole moment (pe), ground state equilibrium bond length and vibrational frequency (ov) for the YbF and pe for the BaF molecule. 

Figure 4.1 Potential energy curves for the molecules AB, AB+, and AB-, showing the ionization energy and electron affinity of AB r is the A-B bond length, and v represents the vibrational quantum number.

Computational levels bond lengths and bond angles, B3LYP/6-31G electrostatic potentials and local ionization energies, HF/6-31GV/B3LYP/6-31G . 

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