Roberto Cammi | Università degli Studi di Parma (Italy) (original) (raw)
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Papers by Roberto Cammi
Journal of Molecular Structure: THEOCHEM, 1991
Theoretical and Computational Chemistry, 1996
Journal of Molecular Structure: THEOCHEM, 1990
ABSTRACT
The journal of physical chemistry. A, Jan 10, 2014
The equilibrium geometry structural and vibrational spectroscopic properties of fullerenes C60 an... more The equilibrium geometry structural and vibrational spectroscopic properties of fullerenes C60 and C70 under high pressure have been studied with a quantum-chemical computational approach in which ab initio calculations on a single fullerene molecule have been carried out within the polarizable continuum model framework to mimic pressure effects. The adopted approach has been revealed effective to explain the geometry variations and the frequency shifts observed experimentally.
Journal of Molecular Structure: THEOCHEM, 2003
We present a theory for the calculation of the self-consistent-field dynamical polarizability and... more We present a theory for the calculation of the self-consistent-field dynamical polarizability and hyperpolarizabilities of molecular solutes described within the framework of the polarization continuum model. The formulation is characterized by the use of a cavity accurately modeled on the molecular shape of the solvated compound, and of a frequency dependent dielectric permittivity for the solvent. Calculations of the components of polarizability α, first and second hyperpolarizabilities β and Γ tensors of H2CO in water and in benzene are reported and discussed.
The computational study of excited states of molecular systems in the condensed phase implies add... more The computational study of excited states of molecular systems in the condensed phase implies additional complications with respect to analogous studies on isolated molecules. Some of them can be faced by a computational modeling based on a continuum (i.e., implicit) description of the solvent. Among this class of methods, the polarizable continuum model (PCM) has widely been used in its basic formulation to study ground state properties of molecular solutes. The consideration of molecular properties of excited states has led to the elaboration of numerous additional features not present in the PCM basic version. Nonequilibrium effects, state-specific versus linear response quantum mechanical description, analytical gradients, and electronic coupling between solvated chromophores are reviewed in the present contribution. The presentation of some selected computational results shows the potentialities of the approach.
ABSTRACT The polarized absorption spectrum of LiNiPO4 crystals is investigated in the range 5000 ... more ABSTRACT The polarized absorption spectrum of LiNiPO4 crystals is investigated in the range 5000 to 25000 cm−1 at 9 K. The splitting and intensities of the bands in different polarizations are interpreted mainly in terms of a C2v perturbation of the octahedral site. The energies of the transitions are reproduced by means of a ligand field calculation, in which only a Oh → C2v site perturbation is considered, assumed as preponderant in the symmetry descent Oh → C2v → Cs.Le spectre d'absorption polarisé des cristaux de LiNiPO4 a été etudié à 9 K dans l'interval 5000 à 25000 cm−1. La separation et l'intensité des bandes dans differentes polarisations ont été interprétées en termes d'une perturbation C2v du site octahedrique. les énergies des transitions ont été reproduites par le moyen d'un calcul du champ des liantes, en tenant compt d'une plus grande contribution Oh → C2v dans le descente de symétrie Oh → C2v → Cs.
Journal of Molecular Structure: THEOCHEM, 1991
Theoretical and Computational Chemistry, 1996
Journal of Molecular Structure: THEOCHEM, 1990
ABSTRACT
The journal of physical chemistry. A, Jan 10, 2014
The equilibrium geometry structural and vibrational spectroscopic properties of fullerenes C60 an... more The equilibrium geometry structural and vibrational spectroscopic properties of fullerenes C60 and C70 under high pressure have been studied with a quantum-chemical computational approach in which ab initio calculations on a single fullerene molecule have been carried out within the polarizable continuum model framework to mimic pressure effects. The adopted approach has been revealed effective to explain the geometry variations and the frequency shifts observed experimentally.
Journal of Molecular Structure: THEOCHEM, 2003
We present a theory for the calculation of the self-consistent-field dynamical polarizability and... more We present a theory for the calculation of the self-consistent-field dynamical polarizability and hyperpolarizabilities of molecular solutes described within the framework of the polarization continuum model. The formulation is characterized by the use of a cavity accurately modeled on the molecular shape of the solvated compound, and of a frequency dependent dielectric permittivity for the solvent. Calculations of the components of polarizability α, first and second hyperpolarizabilities β and Γ tensors of H2CO in water and in benzene are reported and discussed.
The computational study of excited states of molecular systems in the condensed phase implies add... more The computational study of excited states of molecular systems in the condensed phase implies additional complications with respect to analogous studies on isolated molecules. Some of them can be faced by a computational modeling based on a continuum (i.e., implicit) description of the solvent. Among this class of methods, the polarizable continuum model (PCM) has widely been used in its basic formulation to study ground state properties of molecular solutes. The consideration of molecular properties of excited states has led to the elaboration of numerous additional features not present in the PCM basic version. Nonequilibrium effects, state-specific versus linear response quantum mechanical description, analytical gradients, and electronic coupling between solvated chromophores are reviewed in the present contribution. The presentation of some selected computational results shows the potentialities of the approach.
ABSTRACT The polarized absorption spectrum of LiNiPO4 crystals is investigated in the range 5000 ... more ABSTRACT The polarized absorption spectrum of LiNiPO4 crystals is investigated in the range 5000 to 25000 cm−1 at 9 K. The splitting and intensities of the bands in different polarizations are interpreted mainly in terms of a C2v perturbation of the octahedral site. The energies of the transitions are reproduced by means of a ligand field calculation, in which only a Oh → C2v site perturbation is considered, assumed as preponderant in the symmetry descent Oh → C2v → Cs.Le spectre d'absorption polarisé des cristaux de LiNiPO4 a été etudié à 9 K dans l'interval 5000 à 25000 cm−1. La separation et l'intensité des bandes dans differentes polarisations ont été interprétées en termes d'une perturbation C2v du site octahedrique. les énergies des transitions ont été reproduites par le moyen d'un calcul du champ des liantes, en tenant compt d'une plus grande contribution Oh → C2v dans le descente de symétrie Oh → C2v → Cs.