Benefits of Beta-Blockade in Sepsis and Septic Shock: A Systematic Review.

Background: Sepsis and septic shock are inflammatory disorders associated with high rates of mortality. Patients with sepsis and septic shock frequently become tachycardic as a result of the utilization of vasopressor therapy and cardiac overcompensation owing to hypotension, predisposing patients to an increased risk of atrial fibrillation. Previously, it was thought that beta-blocker therapy in patients with sepsis would exacerbate hypotension; however, recent studies have shown that may not be the case.

Role played by isopropyl substituents in stabilizing the putative triple bond in Ar'EEAr' [E = Si, Ge, Sn; Ar' = C6H3-2,6-(C6H3-2,6-Pr(i)2)2] and Ar*PbPbAr* [Ar* = C6H3-2,6-(C6H2-2,4,6-Pr(i)3)2].

A theoretical study of the bonding in ArEEAr (where E = Si, Ge, Sn, Pb; Ar = terphenyl ligand) revealed for the first time why bulky isopropyl substituents electronically are required in order to isolate stable ArEEAr species. This was accomplished by combining the natural orbitals for chemical valence (NOCV) method with the extended transition state (ETS) scheme. The NOCV-ETS analysis was based on two ArE fragments in their doublet ground state with the configuration σ(2)π(1).

Modeling Transition Metal Reactions with Range-Separated Functionals.

The performance of range-separated functionals for the calculation of reaction profiles of organometallic compounds is considered. Sets of high-level computational results are used as reference data for the most part. The benchmark data include a number of reactions involving small molecules reacting with the Pd atom, PdCl(-), PdCl2, and a Ni atom, the reaction of a model Grubbs catalyst, and the ligand binding in a real Grubbs catalyst.

Range-Separated Exchange Functionals with Slater-Type Functions.

An implementation of range-separated density functionals utilizing the Yukawa potential and Slater-type functions is described. The density-functional part of the range-separated regime is straightforward. The exact exchange part makes use of established methods for evaluating exchange integrals over Slater-type functions but still requires new one- and two-center integrals.

Calculation of exchange coupling constants in triply-bridged dinuclear Cu(II) compounds based on spin-flip constricted variational density functional theory.

The performance of the second-order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) for the calculation of the exchange coupling constant (J) is assessed by application to a series of triply bridged Cu(II) dinuclear complexes. A comparison of the J values based on SF-CV(2)-DFT with those obtained by the broken symmetry (BS) DFT method and experiment is provided. It is demonstrated that our methodology constitutes a viable alternative to the BS-DFT method.

Molecular and vibrational structure of tetroxo d0 metal complexes in their excited states. a study based on time-dependent density functional calculations and Franck-Condon theory.

We have applied time dependent density functional theory to study excited state structures of the tetroxo d(0) transition metal complexes MnO(4)(-), TcO(4)(-), RuO(4), and OsO(4). The excited state geometry optimization was based on a newly implemented scheme [Seth et al. Theor.

Calculation of the exchange coupling constants of copper binuclear systems based on spin-flip constricted variational density functional theory.

We have recently developed a methodology for the calculation of exchange coupling constants J in weakly interacting polynuclear metal clusters. The method is based on unrestricted and restricted second order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) and is here applied to eight binuclear copper systems. Comparison of the SF-CV(2)-DFT results with experiment and with results obtained from other DFT and wave function based methods has been made.

First principle simulation of the temperature dependent magnetic circular dichroism of a trinuclear copper complex in the presence of zero field splitting.

We present a test of a recently developed density functional theory (DFT) based methodology for the calculation of magnetic circular dichroism (MCD) spectra in the presence of zero-field splitting (ZFS). The absorption and MCD spectra of the trinuclear copper complex μ(3)O ([Cu(3)(L)(μ(3)-O)](4+)), which models the native intermediate produced in the catalytic cycle of the multicopper oxidases, have been simulated from first principle within the framework of adiabatic time dependent density functional theory. The effects of the ZFS of the quartet (4)A(2) ground state on the theoretical MCD spectrum of μ(3)O have been analyzed.

Bis[(1S)-1,4-azanediyl-1-(9-deazaadenin-9-yl)-1,4-dideoxy-5-methylsulfanyl-D-ribitol] tetrakis(hydrochloride) monohydrate: structure, DFT energy and ligand docking results of a potent methylthioadenosine phosphorylase inhibitor found in different molecular conformations.

The title compound, abbreviated as 5'ThiomethylImmA, is a potent inhibitor of methylthioadenosine phosphorylase [Singh et al. (2004). Biochemistry, 43, 9-18].

Density functional theory study of the magnetic circular dichroism spectra of molybdenyl complexes.

We report a density functional theory (DFT) study of the magnetic circular dichroism (MCD) spectra for four molybdenyl complexes: [MoOCl(4)](-), [MoO(S(2)C(2)H(4))(2)](-), [(Tp*)MoO(bdt)], and [(L3S)MoO(bdt)] (Tp* = hydrotris (3,5-dimethyl-1-pyrazolyl) borate; L3S = (2-dimethylethane-thiolate)bis(3,5-dimethylpyrazolyl)-methane; bdt =1,2-benzenedithiolate). The simulation of the temperature dependent MCD-bands (C-terms) that give rise to the spectra was performed using a method based on time-dependent DFT. In this method, the C-parameters are calculated by including spin-orbit perturbations.

A magnetic and electronic circular dichroism study of azurin, plastocyanin, cucumber basic protein, and nitrite reductase based on time-dependent density functional theory calculations.

The excitation, circular dichroism, magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) spectra of small models of four blue copper proteins are simulated on the TDDFT/BP86 level. X-Ray diffraction geometries are used for the modeling of the blue copper sites in azurin, plastocyanin, cucumber basic protein, and nitrite reductase. Comparison with experimental data reveals that the calculations reproduce most of the qualitative trends of the observed experimental spectra with some discrepancies in the orbital decompositions and the values of the excitation energies, the g( parallel) components of the g tensor, and the components of the A tensor.

Density functional theory study of the electron paramagnetic resonance parameters and the magnetic circular dichroism spectrum for model compounds of dimethyl sulfoxide reductase.

We report a density functional theory (DFT) study of electron paramagnetic resonance (EPR) parameters for complexes modeling the paramagnetic center Mo(V) of the molybdoenzyme dimethyl sulfoxide reductase. We pay special attention to the Mo-OH link to find the most likely geometry and orientation of the metal center in the enzyme and provide an analysis of the physical origin of the g-values in terms of magnetically induced orbital mixing. We also present a study of the magnetic circular dichroism (MCD) spectrum for a complex that models the Mo(V) center of the enzyme.

On the relation between time-dependent and variational density functional theory approaches for the determination of excitation energies and transition moments.

It is shown that it is possible to derive the basic eigenvalue equation of adiabatic time-dependent density functional theory within the Tamm-Dancoff approximation (TD-DFT/TD) from a variational principle. The variational principle is applied to the regular Kohn-Sham formulation of DFT energy expression for a single Slater determinant and leads to the same energy spectrum as TD-DFT/TD. It is further shown that this variational approach affords the same electric and magnetic transition moments as TD-DFT/TD.

A theoretical study of the magnetic circular dichroism spectrum for sulfite oxidase based on time-dependent density functional theory.

We present a theoretical study of the temperature-dependent magnetic circular dichroism (MCD) spectrum for complexes modeling the molybdoenzyme sulfite-oxidase (1) in its Mo(V) oxidation state. The theoretical study was based on a newly implemented time-dependent density functional method that takes into account first-order perturbations due to spin-orbit coupling and a constant magnetic field. It was possible, on the basis of the theoretical calculations, to give a full assignment of the MCD spectrum for 1 and interpret the C term of each band in the experimental MCD spectrum in terms of spin-orbit couplings between specific excited states and between excited states and the ground state.

Magnetic circular dichroism spectrum of plastocyanin by calculation.

The magnetic circular dichroism (MCD) spectrum of the metalloenzyme plastocyanin is calculated using time-dependent density functional theory. The calculation reproduces most of the main features of the experimental spectrum. The calculated spectrum is analyzed to elucidate the contributions to the spectrum and the source of the MCD intensity.

A revised electronic Hessian for approximate time-dependent density functional theory.

Time-dependent density functional theory (TD-DFT) at the generalized gradient level of approximation (GGA) has shown systematic errors in the calculated excitation energies. This is especially the case for energies representing electron transitions between two separated regions of space or between orbitals of different spatial extents. It will be shown that these limitations can be attributed to the electronic ground state Hessian G(GGA).

Application of magnetically perturbed time-dependent density functional theory to magnetic circular dichroism. III. Temperature-dependent magnetic circular dichroism induced by spin-orbit coupling.

A methodology for calculating the temperature-dependent magnetic circular dichroism (MCD) of open-shell molecules with time-dependent density functional theory (TDDFT) is described. The equations for the MCD of an open-shell molecule including spin-orbit coupling in the low- and high-temperature limits are reviewed. Two effects lead to the temperature-dependent MCD: the breaking of degeneracies and the perturbation of transition dipoles by spin-orbit coupling.

Circular dichroism of trigonal dihedral chromium(III) complexes: a theoretical study based on open-shell time-dependent density functional theory.

Spin-unrestricted time-dependent density functional theory has been applied to the electronic circular dichroism spectra of Cr(III) complexes with an open-shell ground state, that is, [Cr(L-L)(3)](n+) with L-L = en(ethylenediamine), acac(acetylacetonate), ox(oxalate), mal(malonate), and Thiox(dithiooxalate). The simulated CD spectra are analyzed in details and compared with experimental data, as well as previous calculations on similar Co(III) complexes where available. The theoretical results serve as a tool for elucidating the absolute configuration of similar complexes, by pointing to transitions for which the sign of the rotatory strength can be used as fingerprint for one particular configuration.

Application of magnetically perturbed time-dependent density functional theory to magnetic circular dichroism. II. Calculation of A terms.

The magnetically perturbed time-dependent density functional theory is used to derive equations for the magnetic circular dichroism (MCD) of degenerate transitions of closed shell molecules. The MCD of this type of transition can be divided into two contributions. The dominant contribution is usually that from A terms that arise because of the breaking of the degeneracy of the excited state in the presence of the magnetic field.

Magnetic circular dichroism of phthalocyanine (m=mg, zn) and tetraazaporphyrin (m=mg, zn, ni) metal complexes. A computational study based on time-dependent density functional theory.

We present here simulated magnetic circular dichroism (MCD) spectra of MTAP (M=Mg, Ni, Zn) and MPc (M=Mg, Zn) where TAP=tetraazaporphyrin and Pc=phthalocyanine. The study is based on magnetically perturbed time-dependent density functional theory (MP-TDDFT) and a newly implemented method for the calculation of A and B terms from the theory of MCD. It follows from our investigation that the MCD spectrum for the MTAP and MPc systems in the Q-band region consists of a single positive A term augmented by a positive B term, in agreement with experiment where available.

Application of magnetically perturbed time-dependent density functional theory to magnetic circular dichroism: calculation of B terms.

Magnetically perturbed time-dependent density functional theory is applied to the calculation of the magnetic circular dichroism (MCD) B terms of closed shell molecules. Two approaches to evaluating B term parameters are described: a sum-over-states-type approach and an approach based on the direct solution of the matrix equations. The advantages and disadvantages and technical challenges of each approach are described.

Calculation of the magnetic circular dichroism B term from the imaginary part of the Verdet constant using damped time-dependent density functional theory.

A time-dependent density functional theory (TDDFT) formalism with damping for the calculation of the magnetic optical rotatory dispersion and magnetic circular dichroism (MCD) from the complex Verdet constant is presented. For a justification of such an approach, we have derived the TDDFT analog of the sum-over-states formula for the Verdet constant. The results of the MCD calculations by this method for ethylene, furan, thiophene, selenophene, tellurophene, and pyrrole are in good agreement with our previous theoretical sum-over-states MCD spectra.

Formulation of magnetically perturbed time-dependent density functional theory.

A formulation of time-dependent density functional theory (TDDFT) in the presence of a static imaginary perturbation is derived. A perturbational approach is applied leading to corrections to various orders in the quantities of interest, namely, the excitation energies and transition densities. The perturbed TDDFT equations are relatively straightforward to derive but the resulting expressions are rather cumbersome.

Magnetic circular dichroism of porphyrins containing M = Ca, Ni, and Zn. A computational study based on time-dependent density functional theory.

A theoretical study is presented on the magnetic circular dichroism (MCD) exhibited by the porphyrin complexes MP (M = Mg,Ni,Zn), MTPP (M = Mg,Ni,Zn), and NiOEP, where P = porphyrin, TPP = tetraphenylporphyrin, and OEP = octaethylporphyrin. The study makes use of a newly implemented method for the calculation of A and B terms from the theory of MCD and is based on time-dependent density functional theory (TD-DFT). It is shown that the MCD spectrum is dominated by a single positive A term in the Q-band region in agreement with experiment where available.

Development of a sum-over-states density functional theory for both electric and magnetic static response properties.

It is shown that it is possible to formulate a sum-over-states (SOS) response theory for static perturbations based directly on the Kohn-Sham formulation of density functional theory (DFT). The SOS-DFT response theory affords expressions analogous to those obtained from the classical Raleigh-Schrodinger perturbation theory, where use is made of a complete set of ground and excited state energies and wave functions. The static SOS-DFT response theory is applicable for both real and imaginary perturbations.