Electronic structure and spectroscopic properties of electronic states of VC2, VC2−, and VC2+

Geometries and electronic structures of nitrogen-doped fullerene fragment C10N2(I) and its ions

The geometries and relative energies of the low-lying electronic states of C(10)N(2)(I), cation, and anion are investigated by the DFT/CCSD(T) method. Vibrational frequency calculation is performed to analyze the stability of optimized geometries of these states. The binding energy, ionization energy, electron affinity of C(10)N(2)(I) and the anion photoelectron spectra are estimated at the CCSD(T)/6-31G(d) level. The ground states of neutral C(10)N(2)(I), cation, and anion are the (1)A(1), (4)B(2), and (2)A(2) states, respectively. The structure of C(10)N(2)(I) can be described as resulting from the fusion of 2 five-numbered rings and 1 six-numbered ring. Results demonstrate that the 2 five-numbered rings are more active than the six-numbered ring in C(10)N(2)(I) during electron excitation and the C(1) atom site within each N(11)-C(1)-C(5)-C(10) unit exhibits more inert than other atom sites during electron ionization and electron attachment.

Geometries, electronic states, and spectroscopic properties of nitrogen-doped fullerene fragment C10N2(II) and its ions

The DFT(B3LYP)/6-31G(d)//CCSD(T)/6-31G(d) method is used to investigate the low-lying electronic states of C(10)N(2)(II) and its ions. Mulliken populations, leading configurations, bond orders, and compositions of molecular orbitals are employed to explore the nature of bonding in the electronic states of C(10)N(2)(II) and its ions. Electron affinity, ionization energy, binding energy of C(10)N(2)(II), and anion photoelectron spectra of C(10)N(2)(II)(-) are also estimated at the CCSD(T)/6-31G(d) level. On the other hand, the similarities and differences between C(10)N(2)(I) and C(10)N(2)(II) are compared and discussed.

Structure and properties of the low-lying electronic states of CeC(2) and CeC(2)(+)

Theoretical studies on the electronic and thermodynamic properties of several electronic states of CeC(2) and CeC(2)(+) have been carried out employing state-of-the-art single- and multireference techniques. The ground and the low-lying electronic states of these two species have been found to possess C(2v) triangular structures. A (3)B(2) state has been found to be the ground state of CeC(2) while for CeC(2)(+) (2)A(2) is the ground state. The computed electron ionization energy is in excellent agreement with experiment. The experimentally observed thermodynamic properties (dissociation and atomization energies) of reactions involving CeC(2) dissociation are corrected using the computed gas-phase properties of the molecule and the partition functions. The bent triplet and singlet state of CeC(2) exhibit large dipole moments (7.0-10.5 D) and it is consistent with the ionic character (through dative charge transfer) of the cluster in ground and excited states.

Geometries and electronic structures of metastable C2N4 and its ions

We carried out the computational studies on the geometric and electronic properties of electronic states of metastable C(2)N(4) (m-C(2)N(4)) and corresponding ions using the CASSCF and DFT(B3LYP)/CCSD(T) techniques. The optimized geometries of electronic states, vibrational frequencies, Mulliken populations, bond orders, and average polarizabilities are computed at the DFT level while the relative energies of the electronic states, ionization energy, electron affinity, binding energy of m-C(2)N(4) are calculated at the CCSD(T) level. The anion photoelectron spectra of m-C(2)N(4)(-) are also predicted. It is interesting to find that the relative energies of the electronic states of m-C(2)N(4) cluster linearly correlate with the amount of charge transfer between N and C atoms and that, however, there is no charge transfer between C and N atoms upon electron ionization or electron attachment.

Structure and Bonding in First-Row Transition Metal Dicarbide Cations MC2+

A theoretical study of the first-row transition metal dicarbide cations MC2+ (M=Sc-Zn) has been carried out. Predictions for different molecular properties that could help in their eventual experimental detection have been made. Most MC2+ compounds prefer a C2v symmetric arrangement over the linear geometry. In particular, the C2v isomer is specially favored for early transition metals. Only for CuC2+ is the linear isomer predicted to be the global minimum, although by only 1 kcal/mol. In all cases the isomerization barrier between cyclic and linear species seems to be very small (below 2 kcal/mol). The topological analysis of the electronic density shows that most C2v isomers are T-shaped structures. In general, MC2+ compounds for early transition metals have larger dissociation energies than those formed by late transition metals. In most cases the dissociation energies for MC2+ compounds are much smaller than those obtained for their neutral analogues. An analysis of the bonding in MC2+ compounds in terms of the interactions between the valence orbitals of the fragments helps to interpret their main features.

Jahn-Teller distortion geometries and electronic structures of Ga3Ge, GaGe3, and their ions

Computational studies on the geometric, electronic, and spectroscopic properties of electronic states are presented for GaGe3, Ga3Ge, and their ions using the CASSCF and DFT(B3LYP)/CCSD(T)/QCISD(T) techniques. The optimized geometries of electronic states, vibrational frequencies, energy separations, Mulliken populations, ionization energies, electron affinities, binding energies are obtained. The anion photoelectron spectra of GaGe3- and Ga3Ge- are predicted. In addition, the results from the low-lying states of GaGe3 and Ga3Ge are compared with those of GaSi3 and Ga3Si. Results demonstrate that the equilibrium geometries of most electronic states of GaGe3, Ga3Ge, and their ions exhibit Jahn-Teller distortion. It is interesting to find that there is not charge transfer between Ga and Ge atoms upon an electron attachment to the ground states of GaGe3 and Ga3Ge, while the amount of charge transfer between Ga and Ge atoms significantly increases upon an electron ionization from the ground state of Ga3Ge.

Structure and Bonding in First-Row Transition-Metal Dicarbides: Are They Related to the Stability of Met-cars?

First-row transition-metal dicarbides MC(2) (M=Sc-Zn) have been investigated by using quantum-mechanical techniques. The competition between cyclic and linear isomers in these systems has been studied and the bonding scheme for these compounds is discussed through topological analysis of electron density. All of the systems have been found to prefer a C(2v)-symmetric arrangement, although for ZnC(2) the energy difference between this and the linear isomer is rather small. In most cases the C(2v)-symmetric structure corresponds to a T-shaped structure, with the exceptions of TiC(2), CoC(2), and NiC(2) which have been shown to be true rings. A detailed analysis of the variation of the energy of the system with geometry has been carried out. An analysis of the bonding, taking into account the main interactions between the valence orbitals of both fragments, the M atom and the C(2) molecule, has allowed the main features of these compounds to be interpreted. A clear correlation between the dissociation energies of the first-row transition-metal dicarbides and the bonding energies of the corresponding met-cars was observed.