Search results for "density functionals"
showing 10 items of 20 documents
Nuclear anapole moment interaction in BaF from relativistic coupled-cluster theory
2018
We present high accuracy relativistic coupled cluster calculations of the P-odd interaction coefficient $W_A$ describing the nuclear anapole moment effect on the molecular electronic structure. The molecule under study, BaF, is considered a promising candidate for the measurement of the nuclear anapole moment, and the preparation for the experiment is now underway [Altunas et al., Phys. Rev. Lett. 120, 142501 (2018)]. Influence of various computational parameters (size of the basis set, treatment of relativistic effects, and treatment of electron correlation) on the calculated $W_A$ coefficient is investigated and a recommended value of 147.7 Hz with an estimated uncertainty of 1.5% is prop…
Binding energies and pairing gaps in semi-magic nuclei obtained using new regularized higher-order EDF generators
2016
We present results of the Hartree-Fock-Bogolyubov calculations performed using nuclear energy density functionals based on regularized functional generators at next-to-leading and next-to-next-to-leading order. We discuss properties of binding energies and pairing gaps determined in semi-magic spherical nuclei. The results are compared with benchmark calculations performed for the functional generator SLyMR0 and functional UNEDF0.
Understanding light-driven H 2 evolution through the electronic tuning of aminopyridine cobalt complexes
2017
A new family of cobalt complexes with the general formula [CoII(OTf)2(Y,XPyMetacn)] (1R,Y,XPyMetacn ¼ 1-[(4-X-3,5-Y-2-pyridyl)methyl]-4,7-dimethyl-1,4,7-triazacyclononane, (X ¼ CN (1CN), CO2Et (1CO2Et), Cl (1Cl), H(1H), NMe2 (1NMe2)) where (Y ¼ H, and X ¼ OMe when Y ¼ Me (1DMM)) is reported. We found that the electronic tuning of the Y,XPyMetacn ligand not only has an impact on the electronic and structural properties of the metal center, but also allows for a systematic water-reduction-catalytic control. In particular, the increase of the electron-withdrawing character of the pyridine moiety promotes a 20-fold enhancement of the catalytic outcome. By UV-Vis spectroscopy, luminescence quenc…
Vibrational Sum Frequency Generation Spectroscopy of the Water Liquid–Vapor Interface from Density Functional Theory-Based Molecular Dynamics Simulat…
2013
International audience; The vibrational sum frequency generation (VSFG) spectrum of the water liquid-vapor (LV) interface is calculated using density functional theory-based molecular dynamics simulations. The real and imaginary parts of the spectrum are in good agreement with the experimental data, and we provide an assignment of the SFG bands according to the dipole orientation of the interfacial water molecules. We use an instantaneous definition of the surface, which is more adapted to the study of interfacial phenomena than the Gibbs dividing surface. By calculating the vibrational (infrared, Raman) properties for interfaces of varying thickness, we show that the bulk spectra signature…
Metal-Controlled Magnetoresistance at Room Temperature in Single-Molecule Devices
2017
The appropriate choice of the transition metal complex and metal surface electronic structure opens the possibility to control the spin of the charge carriers through the resulting hybrid molecule/metal spinterface in a single-molecule electrical contact at room temperature. The single-molecule conductance of a Au/molecule/Ni junction can be switched by flipping the magnetization direction of the ferromagnetic electrode. The requirements of the molecule include not just the presence of unpaired electrons: the electronic configuration of the metal center has to provide occupied or empty orbitals that strongly interact with the junction metal electrodes and that are close in energy to their F…
Role of Solvent on Nonenzymatic Peptide Bond Formation Mechanisms and Kinetic Isotope Effects
2013
Based on the hypothesis that similar mechanisms are involved in the peptide bond formation in aqueous solution and in the ribosome, the aminolysis of esters in aqueous solution has been the subject of numerous studies as the reference reaction for the catalyzed process. The mechanisms proposed in the literature have been explored in the present paper by hybrid QM/MM molecular dynamics simulations. The free energy profiles have been computed with the QM region of the system described at semiempirical AM1 level and by DFT within the M06-2X functional. According to the results, the formation of adduct zwitterion species is a preliminary step required for all possible mechanisms. Then, from dif…
Molecular Rearrangement of an Aza-Scorpiand Macrocycle Induced by pH: A Computational Study †
2016
Rearrangements and their control are a hot topic in supramolecular chemistry due to the possibilities that these phenomena open in the design of synthetic receptors and molecular machines. Macrocycle aza-scorpiands constitute an interesting system that can reorganize their spatial structure depending on pH variations or the presence of metal cations. In this study, the relative stabilities of these conformations were predicted computationally by semi-empirical and density functional theory approximations, and the reorganization from closed to open conformations was simulated by using the Monte Carlo multiple minimum method Financial support by the Spanish Ministerio de Economía y Competitiv…
Accurate Treatment of Large Supramolecular Complexes by Double-Hybrid Density Functionals Coupled with Nonlocal van der Waals Corrections.
2015
In this work, we present a thorough assessment of the performance of some representative double-hybrid density functionals (revPBE0-DH-NL and B2PLYP-NL) as well as their parent hybrid and GGA counterparts, in combination with the most modern version of the nonlocal (NL) van der Waals correction to describe very large weakly interacting molecular systems dominated by noncovalent interactions. Prior to the assessment, an accurate and homogeneous set of reference interaction energies was computed for the supramolecular complexes constituting the L7 and S12L data sets by using the novel, precise, and efficient DLPNO-CCSD(T) method at the complete basis set limit (CBS). The correction of the bas…
Mean-Field Calculation Based on Proton-Neutron Mixed Energy Density Functionals
2014
We have performed calculations based on the Skyrme energy density functional (EDF) that includes arbitrary mixing between protons and neutrons. In this framework, single-particle states are generalized as mixtures of proton and neutron components. The model assumes that the Skyrme EDF is invariant under the rotation in isospin space and the Coulomb force is the only source of the isospin symmetry breaking. To control the isospin of the system, we employ the isocranking method, which is analogous to the standard cranking approach used for describing high-spin states. Here, we present results of the isocranking calculations performed for the isobaric analog states in $A = 40$ and $A = 54$ nuc…
Structure of transactinide nuclei with relativistic energy density functionals
2013
A microscopic theoretical framework based on relativistic energy density functionals (REDFs) is applied to studies of shape evolution, excitation spectra, and decay properties of transactinide nuclei. Axially symmetric and triaxial relativistic Hartree-Bogoliubov (RHB) calculations, based on the functional DD-PC1 and with a separable pairing interaction, are performed for the even-even isotopic chains between Fm and Fl. The occurrence of a deformed shell gap at neutron number $N=162$ and its role on the stability of nuclei in the region around $Z=108$ is investigated. A quadrupole collective Hamiltonian, with parameters determined by self-consistent constrained triaxial RHB calculations, is…