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We present a time-dependent density functional theory (TDDFT) based approach to compute the light-matter couplings between two different manifolds of excited states relative to a common ground state. These quantities are the necessary ingredients to solve the Kramers--Heisenberg equation for resonant inelastic X-ray scattering (RIXS) and several other types of two-photon spectroscopies. The procedure is based on the pseudo-wavefunction approach, where TDDFT eigenstates are treated as a configuration interaction wavefunction with single excitations, and on the restricted energy window approach, where a manifold of excited states can be rigorously defined based on the energies of the occupied molecular orbitals involved in the excitation process. We illustrate the applicability of the method by calculating the 2p4d RIXS maps of three representative Ruthenium complexes and comparing them to experimental results. The method is able to accurately capture all the experimental features in all three complexes, with relative energies correct to within 0.6 eV at the cost of two independent TDDFT calculations.

The Chronus Quantum (ChronusQ) software package is an open source (under the GNU General Public License v2) software infrastructure which targets the solution of challenging problems that arise in ab initio electronic structure theory. Special emphasis is placed on the consistent treatment of time dependence and spin in the electronic wave function, as well as the inclusion of relativistic effects in said treatments. In addition, ChronusQ provides support for the inclusion of uniform finite magnetic fields as external perturbations through the use of gauge-including atomic orbitals (GIAO). ChronusQ is a parallel electronic structure code written in modern C++ which utilizes both message passing (MPI) and shared memory (OpenMP) parallelism. In addition to the examination of the current state of code base itself, a discussion regarding ongoing developments and developer contributions will also be provided., Comment: 43 pages, 2 figures

The Hartree-Fock problem was recently recast as a semidefinite optimization over the space of rank-constrained two-body reduced-density matrices (RDMs) [Phys. Rev. A 89, 010502(R) (2014)]. This formulation of the problem transfers the non-convexity of the Hartree-Fock energy functional to the rank constraint on the two-body RDM. We consider an equivalent optimization over the space of positive semidefinite one-electron RDMs (1-RDMs) that retains the non-convexity of the Hartree-Fock energy expression. The optimized 1-RDM satisfies ensemble $N$-representability conditions, and ensemble spin-state conditions may be imposed as well. The spin-state conditions place additional linear and nonlinear constraints on the 1-RDM. We apply this RDM-based approach to several molecular systems and explore its spatial (point group) and spin ($S^2$ and $S_3$) symmetry breaking properties. When imposing $S^2$ and $S_3$ symmetry but relaxing point group symmetry, the procedure often locates spatial-symmetry-broken solutions that are difficult to identify using standard algorithms. For example, the RDM-based approach yields a smooth, spatial-symmetry-broken potential energy curve for the well-known Be--H$_2$ insertion pathway. We also demonstrate numerically that, upon relaxation of $S^2$ and $S_3$ symmetry constraints, the RDM-based approach is equivalent to real-valued generalized Hartree-Fock theory., 9 pages, 6 figures

Este artículo presenta una integración del proceso de licenciamiento ambiental aplicada a Río de Janeiro (Brasil) a través del documento de Estudio e Informe de Impacto Ambiental (EIA/RIMA). Se analiza también la estructuración de las recomendaciones sobre prácticas de gestión de proyectos de acuerdo Instituto de Gestión de Proyectos en las etapas de iniciación, planificación, ejecución, control y cierre. Esto se hace con el fin de identificar la eficiencia en los procesos de integración, las partes interesadas, alcance, tiempo, calidad, costo y la comunicación en el plan de gestión de la EIA/RIMA. Se realizó una contextualización de las políticas de licenciamiento ambiental nacional, estatal y local en Brasil, que son cruciales en la elaboración del estudio de impacto ambiental. La integración de la gestión de proyectos y documentos de gestión ambiental contribuye a formar equipos más comprometidos con responsabilidades ambientales presentes en los planes de trabajo para proyectos ambientales. This paper presents an integration of the process of environmental licensing applied to Rio de Janeiro (Brazil) through the document Study and Report of Environmental Impact (EIA/RIMA). Also, the study analyzes the structuring of the recommendations of project management practices according to the Project Management Institute in the stages of initiation, planning, execution, control and closure. This is done to identify the efficiency in integration processes, stakeholders, scope, time, quality, cost and communication in the document project management plan EIA/RIMA. The contextualization of the national, state and local environmental licensing policies in Brazil was done. These are crucial in the making of the Environmental Impact Study. The integration of project management and environmental management documents contributes to form teams that are more committed with environmental responsibilities present in the work plans of environmental projects.