Showing papers by "Ernest R. Davidson published in 1975"
2,265 citations
TL;DR: The Video Fluorometer as mentioned in this paper is a new instrument for fluorescence analysis which offers significant advantages for the study of complex systems and can acquire 241 fluorescence spectra, taken at 241 different exciting wavelengths in 16.7 milliseconds.
Abstract: The Video Fluorometer is a new instrument for fluorescence analysis which offers significant advantages for the study of complex systems. This instrument can acquire 241 fluorescence spectra, taken at 241 different exciting wavelengths in 16.7 milliseconds. These results are displayed in a three-dimensional graphical format in real time. Coupled with a laboratory computer, this instrument should provide new algorithms for the analysis of luminescence spectra of multi-component systems.
62 citations
TL;DR: The zero field splitting (zfs) for porphyrin is calculated for possible transitions b2u(π), a1uπ, a 1uπ and a 2uπ → eg(π*).
Abstract: The zero field splitting (zfs) for porphyrin is calculated for possible transitions b2u(π), a1u(π), a2u(π) → eg(π*). Calculations are done with pi−electron orbital coefficients determined from extended Huckel calculations on the deprotonated dianion, the free base, and the acid dication. The spin dipole−dipole couplings are evaluated exactly using a Gaussian−lobe expansion. The calculations are compared to the reported zfs of zinc and free base porphin and to the zfs reported herein of Zn etioporphyrin in various lattice sites in an octane matrix and of Zn tetraphenylporphin. The calculations fit experimental D and E values within 10% under the following assumptions: (i) For Zn etioporphyrin and Zn porphin the triplet state is 3[a1u(π) → eg(π*)], but for Zn tetraphenylporphin it is 3[a2u(π) → eg(π*)]; (ii) the larger value for D observed in free base porphin is due to configuration interaction between these two transitions; (iii) variable axis directions set up by the lattice crystal field cause the varia...
58 citations
TL;DR: In this article, double cosets are used to reduce the formulas for integrals over symmetry orbitals to unique integrals on atomic orbitals, which are then used to construct the double coset.
Abstract: Double cosets are used to reduce the formulas for integrals over symmetry orbitals to unique integrals over atomic orbitals.
50 citations
TL;DR: In this paper, the electron spin dipole-dipole contribution to zero-field splitting of benzene in its lowest triplet state (3B1u in D6h symmetry) was determined theoretically by ab initio methods.
Abstract: The electron spin dipole–dipole contribution to the zero‐field splitting of benzene in its lowest triplet state (3B1u in D6h symmetry) is determined theoretically by ab initio methods. Two hexagonal conformations are considered, distinguished by having carbon–carbon bond lengths appropriate to the 1A1g ground state (1.395 A) and to the 3B1u state (1.427 A). In addition, two distorted forms of D2h symmetry are treated, one having a compressed or ’’quinoidal’’ structure and the other having an elongated structure. All calculations are carried out with a double‐zeta basis of contracted Gaussian‐lobe functions. The correct microscopic spin‐dipole Hamiltonian is used and all integrals are evaluated accurately. The hexagonal conformation with 1.427 A bond lengths gives results in best agreement with experiment. A large configuration‐interaction wavefunction leads to D=0.1676 cm−1, to be compared with D=0.1580 cm−1 obtained from the electron resonance spectra of benzene in a C6D6 host crystal. Both the quinoid a...
34 citations
TL;DR: An ab initio SCF-CI wavefunction for the 2A1 ground state of NO2 has been calculated using a "double zeta plus polarization" quality basis set as discussed by the authors.
Abstract: An ab initio SCF–CI wavefunction for the 2A1 ground state of NO2 has been calculated using a ’’double zeta plus polarization’’ quality basis set. The CI energy, −204.374346 a.u., is the lowest which has been reported for this molecule. The CI wavefunction is discussed and Mulliken population analyses are presented. Several one‐electron properties, including the magnetic hyperfine splitting parameters, are reported for both the SCF and CI wavefunction.
33 citations
TL;DR: In this paper, a new scheme for constructing L2, Lz, S2, Sz eigenfunctions within the Hartree-Fock interacting subspace has been used to generate a first-order configuration-interaction wavefunction for the ground 4F state of the vanadium atom in the nonrelativistic approximation.
Abstract: A new scheme for constructing L2, Lz, S2, Sz eigenfunctions within the Hartree–Fock interacting subspace has been used to generate a first‐order configuration‐interaction wavefunction for the ground 4F state of the vanadium atom in the nonrelativistic approximation. The basis set consisted of 62 Slater‐type orbitals, with l up to 5, transformed to Hartree–Fock orbitals in the ’’occupied’’ subspace and to pseudonatural orbitals in the ’’virtual’’ subspace. Approximately 70% of the correlation energy was recovered with 500 configurations (1023 terms formed from 31 496 Slater determinants). The charge density, momentum density, x‐ray scattering factor, and Compton profile were computed from both the CI and SCF wavefunctions.
19 citations
TL;DR: In this article, the contributions of spin polarization and spin delocalization mechanisms to the proton hyperfine coupling constant were investigated and it was shown that these non-observables are not uniquely defined in most calculations.
12 citations