Current density maps, magnetizability, and nuclear magnetic shielding tensors of bis-heteropentalenes. II. Furo-furan Isomers

Magnetic susceptibility and nuclear magnetic shielding at the nuclei of bis-heteropentalenes formed by two furan units ([2,3-b], [3,2-b], [3,4-b], and [3,4-c] isomers) have been computed by several approximated techniques and a large Gaussian basis set to achieve near Hartree–Fock estimates. Ab initio models of the ring currents induced by a magnetic field normal to the molecular plane were obtained for the three isomeric systems of higher symmetry, showing that the π electrons give rise to intense diamagnetic circulation. The π currents are responsible for enhanced magnetic anisotropy and strong out-of-plane proton deshielding. The theoretical findings are used to build up a “diatropicity matrix” for two fused five-membered heterocyclic [email protected] ; [email protected]

Lower Rydberg series of methane : A combined coupled cluster linear response and molecular quantum defect orbital calculation

Vertical excitation energies as well as related absolute photoabsorption oscillator strength data are very scarce in the literature for methane. In this study, we have characterized the three existing series of low-lying Rydberg states of CH4 by computing coupled cluster linear response (CCLR) vertical excitation energies together with oscillator strengths in the molecular-adapted quantum defect orbital formalism from a distorted Cs geometry selected on the basis of outer valence green function calculations. The present work provides a wide range of data of excitation energies and absolute oscillator strengths which correspond to the Rydberg series converging to the three lower ionization potential values of the distorted methane molecule, in energy regions for which experimentally measured data appear to be [email protected] [email protected] [email protected]

Assessment of the CTOCD-DZ methodin a hierarchy of coupled cluster methods

A systematic study in a hierarchy of coupled cluster methods has been carried out for the first time in order to investigate the performance of the CTOCD-DZ approach to compute NMR magnetic shielding constants. Results show that CTOCD-DZ is competitive with other ab initio methods, in particular with those using the GIAO approach. Deviations with respect to experiment are of the order of 1-2 ppm, a difference that is of the order of the vibrational effects that we have not taken into account. We find specially relevant that in many cases even CC2 calculations can be sufficient, which opens the chance of studying large molecular systems through the use of the already implemented Cholesky decomposition-based methods

Erratum: “Density-functional and electron correlated study of five linear birefringences—Kerr, Cotton–Mouton, Buckingham, Jones and magnetoelectric—in gaseous benzene” J. Chem. Phys. 121, 8814 2004; “Density-functional study of electric and magnetic properties of hexafluorobenzene in the vapor phase” J. Chem. Phys. 122, 234314 2005; and “A computational study of some electric and magnetic properties of gaseous BF3 and BCl3” J. Chem. Phys. 123, 114307 2005

Erratum: “Density-functional and electron correlated study of five linear birefringences—Kerr, Cotton–Mouton, Buckingham, Jones and magnetoelectric—in gaseous benzene” †J. Chem. Phys. 121, 8814 „2004…‡; “Density-functional study of electric and magnetic properties of hexafluorobenzene in the vapor phase” †J. Chem. Phys. 122, 234314 „2005…‡; and “A computational study of some electric and magnetic properties of gaseous BF3 and BCl3” †J. Chem. Phys. 123, 114307 „2005…

A computational study of some electric and magnetic properties of gaseous BF3 and BCl3

We present the results of an extended computational study of the electric and magnetic properties connected to Cotton-Mouton birefringences, on the trifluoro- and trichloroborides in the gas phase. The electric dipole polarizabilities, magnetizabilities, quadrupole moments, and higher-order hypersusceptibilities—expressed as quadratic and cubic frequency-dependent response functions— are computed within Hartree-Fock, density-functional, and coupled-cluster response theories employing singly and doubly augmented correlation-consistent basis sets and London orbitals in the magnetic property calculations. The results, which illustrate the capability of time-dependent density-functional theory for electron-rich systems, are compared with available experimental data. Revised values of both experimentally derived quadrupole moment of BF3, 2.72±0.15 a.u., and magnetizability anisotropy of BCl3, −0.45±0.09 a.u., both obtained in birefringence experiments that neglect the effects of higher-order hypersusceptibilities, are presented. In the theoretical limit the traceless quadrupole moments of BF3 and BCl3 are determined to be 3.00±0.01 and 0.71±0.01 a.u., respectively