Search results for "Calculation"

Theoretical study of the effect of substituent and backbone conformation on the electronic properties of symmetrically substituted poly(di‐n‐alkylsil…

1994

We present the results of ab initio 3‐21G∗ geometry optimizations and valence effective Hamiltonian (VEH) band structure calculations aimed at determining the evolution of the geometric and electronic (ionization potential, electron affinities, and band gaps) properties of all‐trans poly(dimethylsilane), poly(diethylsilane), poly(di‐n‐propylsilane), and poly(di‐n‐butylsilane) when increasing the size of the alkyl group. In the latter polymer, we have also studied the 7/3 conformation, in order to analyze the effect of the backbone conformation on the geometric and electronic structure. The VEH ionization potentials of all‐trans poly(di‐n‐alkylsilanes) are almost equal, and as experimental p…

Dosing fentanyl buccal tablet for breakthrough cancer pain: dose titration versus proportional doses.

2012

Abstract OBJECTIVES: The aim of this study was to compare the efficacy and safety of doses of fentanyl buccal tablet (FBT) proportional to doses of opioids used for background analgesia versus dose titration starting with the minimal dose for the management of breakthrough cancer pain (BTcP). METHODS: A total of 82 cancer patients with BTcP who were receiving strong opioids in doses of at least 60 mg of oral morphine equivalents and having acceptable background analgesia, were selected for a multicenter unblinded study. Forty-one patients were randomized to receive FBT in doses proportional to the daily opioid doses for four consecutive episodes of BTcP (group P). Forty-one patients underwe…

Dicopper(II) Metallacyclophanes with Electroswitchable Polymethyl-Substitutedpara-Phenylene Spacers

2013

Double-stranded anionic dinuclear copper(II) metallacyclic complexes of the paracyclophane type [Cu2L2]4- have been prepared by the CuII-mediated self-assembly of different para-phenylenebis(oxamato) bridging ligands with either zero-, one-, or four-electron-donating methyl substituents (L=N,N′-para- phenylenebis(oxamate) (ppba; 1), 2-methyl- N,N′-para-phenylenebis(oxamate) (Meppba; 2), and 2,3,5,6-tetramethyl- N,N′-para-phenylenebis(oxamate) (Me4ppba; 3)). These complexes have been isolated as their tetra-n-butylammonium (1 a-3 a), lithium(I) (1 b-3 b), and tetraphenylphosphonium salts (1 c-3 c). The X-ray crystal structures of 1 a and 3 c show a parallel-displaced π-stacked conformation w…

Carbon–Phosphorus Coupling from C^N Cyclometalated Au III Complexes

2020

Abstract With the aim of exploiting new organometallic species for cross‐coupling reactions, we report here on the AuIII‐mediated Caryl−P bond formation occurring upon reaction of C^N cyclometalated AuIII complexes with phosphines. The [Au(C^N)Cl2] complex 1 featuring the bidentate 2‐benzoylpyridine (CCON) scaffold was found to react with PTA (1,3,5‐triaza‐7‐phosphaadamantane) under mild conditions, including in water, to afford the corresponding phosphonium 5 through C−P reductive elimination. A mechanism is proposed for the title reaction based on in situ 31P{1H} NMR and HR‐ESI‐MS analyses combined with DFT calculations. The C−P coupling has been generalized to other C^N cyclometalated Au…

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

2006

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 p…

Structure Sensitivity of 2‐Methyl--butyn-2-ol Hydrogenation on Pd: Computational and Experimental Modeling

2014

General Flavor Blind MSSM and CP Violation

2001

We study the implications on flavor changing neutral current and CP violating processes in the context of supersymmetric theories without a new flavor structure (flavor blind supersymmetry). The low energy parameters are determined by the running of the soft breaking terms from the grand unified scale with SUSY phases consistent with the EDM constraints. We find that the CP asymmetry in b --> s gamma can reach large values potentially measurable at B factories, especially in the low BR(b --> s gamma) region. We perform a fit of the unitarity triangle including all the relevant observables. In this case, no sizeable deviations from the SM expectations are found. Finally we analyze the …

Measurement of the ZZ cross-section in e(+)e(-) interactions at 183-189 GeV

2001

Measurements of on-shell ZZ production are described, using data collected by DELPHI in 1997 and 1998, at centre-of-mass energies sqrt(s) = 182.6 GeV and 188.6 GeV respectively. Results obtained in each of the final states q qbar q qbar, mu+mu- q qbar, e+e- q qbar, nu nubar q qbar, l+l-l+l-, and nu nubar l+l- are presented. The measured cross-sections for on-shell ZZ production via the tree-level doubly-resonant graphs (NC02) are: sigma_{NC02}(182.6 GeV) = 0.38 +- 0.18 (stat) +- 0.04 (syst) pb, sigma_{NC02}(188.6 GeV) = 0.60 +- 0.13 (stat) +- 0.07 (syst) pb. They are consistent with the Standard Model expectations of 0.25 pb and 0.65 pb at each energy.

Effective Majorana mass matrix from tau and pseudoscalar meson lepton number violating decays

2018

An observation of any lepton number violating process will undoubtedly point towards the existence of new physics and indirectly to the clear Majorana nature of the exchanged fermion. In this work, we explore the potential of a minimal extension of the Standard Model via heavy sterile fermions with masses in the $[ 0.1 - 10]$ GeV range concerning an extensive array of "neutrinoless" meson and tau decay processes. We assume that the Majorana neutrinos are produced on-shell, and focus on three-body decays. We conduct an update on the bounds on the active-sterile mixing elements, $|U_{\ell_\alpha 4} U_{\ell_\beta 4}|$, taking into account the most recent experimental bounds (and constraints) a…

Inclusive B-meson production at small p_T in the general-mass variable-flavor-number scheme

2015

We calculate the cross section for the inclusive production of B mesons in pp and ppbar collisions at next-to-leading order in the general-mass variable-flavor-number scheme and show that a suitable choice of factorization scales leads to a smooth transition to the fixed-flavor-number scheme. Our numerical results are in good agreement with data from the Tevatron and LHC experiments at small and at large transverse momenta.