Nonrelativistic and quasirelativisticab initio pseudopotentials substituting the M(Z−28)+-core orbitals of the second row transition elements and the M(Z−60)+-core orbitals of the third row transition elements, respectively, and optimized (8s7p6d)/[6s5p3d]-GTO valence basis sets for use in molecular calculations have been generated. Additionally, corresponding spin-orbit operators have also been derived. Atomic excitation and ionization energies from numerical HF as well as from SCF pseudopotential calculations using the derived basis sets differ in most cases by less than 0.1 eV from corresponding numerical all-electron results. Spin-orbit splittings for lowlying states are in reasonable agreement with corresponding all-electron Dirac-Fock (DF) results.

Energy-adjustedab initio pseudopotentials for the second and third row transition elements

Azobenzene undergoes trans → cisisomerization when irradiated with light tuned to an appropriate wavelength. The reverse cis →transisomerization can be driven by light or occurs thermally in the dark. Azobenzene's photochromatic properties make it an ideal component of numerous molecular devices and functional materials. Despite the abundance of application-driven research, azobenzene photochemistry and the isomerization mechanism remain topics of investigation. Additional substituents on the azobenzene ring system change the spectroscopic properties and isomerization mechanism. This critical review details the studies completed to date on the 3 main classes of azobenzene derivatives. Understanding the differences in photochemistry, which originate from substitution, is imperative in exploiting azobenzene in the desired applications.

Photoisomerization in different classes of azobenzene

We present nonrelativistic and quasirelativistic energy‐adjusted pseudopotentials, the latter augmented by spin–orbit operators, as well as optimized (12s11p10d8f)/ [8s7p6d4f]‐Gaussian‐type orbitals (GTO) valence basis sets for the actinide elements actinium through lawrencium. Atomic excitation and ionization energies obtained by the use of these pseudopotentials and basis sets in self‐consistent field (SCF) calculations differ by less than 0.2 eV from corresponding finite‐difference all‐electron results. Large‐scale multiconfiguration self‐consistent field (MCSCF), multireference configuration interaction (MRCI), and multireference averaged coupled‐pair functional (MRACPF) calculations for thorium and thorium monoxide yield results in satisfactory agreement with available experimental data. Preliminary results from spin–orbit configuration interaction calculations for the low‐lying electronic states of thorium monoxide are also reported.

Energy‐adjusted pseudopotentials for the actinides. Parameter sets and test calculations for thorium and thorium monoxide

In this report, we summarize and describe the recent unique updates and additions to the Molcas quantum chemistry program suite as contained in release version 8. These updates include natural and spin orbitals for studies of magnetic properties, local and linear scaling methods for the Douglas-Kroll-Hess transformation, the generalized active space concept in MCSCF methods, a combination of multiconfigurational wave functions with density functional theory in the MC-PDFT method, additional methods for computation of magnetic properties, methods for diabatization, analytical gradients of state average complete active space SCF in association with density fitting, methods for constrained fragment optimization, large-scale parallel multireference configuration interaction including analytic gradients via the interface to the Columbus package, and approximations of the CASPT2 method to be used for computations of large systems. In addition, the report includes the description of a computational machinery for nonlinear optical spectroscopy through an interface to the QM/MM package Cobramm. Further, a module to run molecular dynamics simulations is added, two surface hopping algorithms are included to enable nonadiabatic calculations, and the DQ method for diabatization is added. Finally, we report on the subject of improvements with respects to alternative file options and parallelization.

https://hal-amu.archives-ouvertes.fr/hal-01409053/document

Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table.

Nonrelativistic and quasirelativistic energy‐adjusted ab initio pseudopotentials substituting the 1s–3d core orbitals with corresponding spin–orbit operators for the rare earth elements Ce through Yb have been generated. Excitation and ionization energies from numerical pseudopotential calculations differ by less than 0.1 eV from corresponding numerical all–electron results. The pseudopotentials for Ce have been tested in molecular calculations for the 3Φ ground state of CeO. The derived spectroscopic constants from quasirelativistic pseudopotential CI(SD) calculations including Davidson’s correction (Re=1.827 A, De=6.95 eV, ωe=834 cm−1) are in good agreement with experimental values (Re=1.820 A, De=8.19 eV, ωe=862 cm−1).

Energy‐adjusted ab initio pseudopotentials for the rare earth elements

Methods are derived to simplify and expand the scope of ab initio electronic-structure calculations using relativistic core potentials. The spin-orbit operator obtained at the same level of approximation is expressed in a simpler form to facilitate matrix-element computation. Double-group results are used, when sufficient spatial symmetry is present, both to block the Hamiltonian matrix and to make it real, even though the wave functions are necessarily complex.

Electronic-structure methods for heavy-atom molecules

Theoretical assignments of the low-lying electronic states of carbon dioxide

We report the results of extensive configuration interaction studies on 16 excited states of water. These states can be accurately described as corresponding to excitation from one of the highest two molecular orbitals (1b_1 or 3a_1) of the ground state into either the 3s or one of the three 3p Rydberg orbitals. The results provide the most accurate and consistent treatment of these states to date (within 0.1 eV for all known transitions) and form a reliable basis for the assignment of the photon and electron impact spectra of H_2O.

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Configuration interaction studies of the excited states of water

Hartree—Fock calculation of the barrier to internal rotation in hydrogen peroxide

The N2H2 molecule is only metastable and as a consequence is not well characterized experimentally. Therefore, we have carried out extensive Hartree-Fock calculations in order to determine equilibrium geometries, one-electron properties, and the relative energies of the cis and trans isomers. In addition, Hartree-Fock and multiconfiguration calculations were carried out to determine the mechanism for isomerization. The trans isomer was found to be 6.6 kcal/mole more stable than the cis form using a basis set which included polarization functions. The lowest energy path found for isomerization occurred by inversion about one nitrogen (rather than rotation about the NN bond) with an activation energy of 47 kcal/mole. Excitation energies for the lowest singlet and triplet excited states are also presented.

Nicholas W. Winter

Papers

Electronic-structure methods for heavy-atom molecules

Theoretical assignments of the low-lying electronic states of carbon dioxide

Configuration interaction studies of the excited states of water

Hartree—Fock calculation of the barrier to internal rotation in hydrogen peroxide

Theoretical description of the diimide molecule