Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We extend our recently reported embedding theory [J. Chem. Phys. 110, 7677 (1999)] to calculate not only improved descriptions of ground states, but now also localized excited states in a periodically infinite condensed phase. A local region of the solid is represented by a small cluster for which high quality quantum chemical calculations are performed. The interaction of the cluster with the extended condensed phase is taken into account by an effective embedding potential. This potential is calculated by periodic density functional theory (DFT) and is used as a one-electron operator in subsequent cluster calculations. Among a variety of benchmark calculations, we investigate a CO molecule adsorbed on a Pd(111) surface. By performing complete active space self-consistent field, configuration interaction (CI), and Møller–Plesset perturbation theory of order n (MP-n), we not only were able to obtain accurate adsorption energies via local corrections to DFT, but also vertical excitation energies for an internal (5σ→2π*) excitation within the adsorbed CO molecule. We demonstrate that our new scheme is an efficient and accurate approach for the calculation of local excited states in bulk metals and on metal surfaces. Additionally, a systematic means of improving locally on ground state properties is provided. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Molecular dynamics simulations and fluorescence anisotropy decay measurements are used to investigate the rotational diffusion of anthracene in two organic solvents—cyclohexane and 2-propanol—at several temperatures. Molecular dynamics simulations of 1 ns length were performed for anthracene in cyclohexane (at 280, 296, and 310 K) and in 2-propanol (at 296 K). The calculated time constants for reorientation of the short in-plane axis were 7–9 and 11–16 ps at 296 K in cyclohexane and 2-propanol, respectively, in excellent agreement with corresponding fluorescence depolarization measurements of 8 and 14 ps. The measured rotational reorientation times and the calculated average rotational diffusion coefficients varied in accord with Debye–Stokes–Einstein theory. Their magnitudes were close to values predicted for an ellipsoid of shape and size equivalent to an anthracene molecule, and exhibited predictable variation with external conditions—increasing with temperature and decreasing with solvent viscosity. However, analysis of the calculated rotational diffusion coefficients for the individual molecular axes gave a more complex picture. The diffusion was highly anisotropic and changes in temperature and solvent type led to nonuniform variation of the diffusion coefficients. The nature of these changes was rationalized based on analysis of variation of solvation patterns with temperature and solvent. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 104 (1996), S. 1-6 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Depolarized low-frequency Raman spectra of aqueous solutions of L-xyloascorbic acid and its epimer D-araboascorbic acid have been investigated as a function of concentration at 30 °C. The influence of fluorescence in the low-frequency Raman spectral intensity of D-araboascorbic acid aqueous solution was removed by the background correction. The reduced χ″(ν¯) spectrum, which corresponds to the imaginary part of the dynamical susceptibility due to the dynamical structure of water in aqueous solutions, was analyzed with the superposition of one Cole–Cole type relaxation mode and two damped harmonic oscillator modes. The effect of L-xyloascorbic acid on the dynamical structure of water is less than that of D-araboascorbic acid. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 88-91 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Immunopurified human p53 protein was phosphorylated in vitro by several immunopurified cyclin-dependent kinase complexes: cyclin Dl/Cdk4, cyclin B/Cdc2, cyclin A/Cdk2 or cyclin E/Cdk2 (Fig. \d). Purified Rb protein (Fig. 10, bottom panel) was used to standardize the activity of the four ...
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 100 (1994), S. 2407-2412 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Low-frequency depolarized Raman spectra of aqueous solutions of D-glucose and D-galactose have been investigated in the frequency region from −250 cm−1 to 250 cm−1 at 30.0 °C as a function of concentration up to 0.04 molar ratio. The dynamical structure of water in aqueous solution is analyzed by using the reduced Raman spectrum χ‘(ν¯), which corresponds to the imaginary part of the dynamical susceptibility. The reduced spectrum is fitted with the superposition of one Cole–Cole type relaxation mode and two damped harmonic oscillator modes by a nonlinear least-squares fitting. The effects of D-glucose and D-galactose on the dynamical structure of water in aqueous solution are similar. The relaxation time of hydrogen bond among water molecules becomes slower with increasing sugar concentration. The characteristic frequencies of stretching-like and bending-like vibrations among water molecules do not change in both D-glucose and D-galactose aqueous solutions.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 3110-3112 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A thin film structure with Ag nanocrystallites embedded in a polycrystalline C60 matrix was grown under high vacuum by codeposition of Ag and C60 onto the hot substrate. The structural and physical properties of the film were characterized by a transmission electron microscope and a Raman scattering spectrometer. The Ag nanoparticles were well dispersed and not aggregated. An ordered nanoscale C60 lattice was observed between the two adjacent Ag particles, and the Raman-active Ag(2) pentagonal-pinch mode of C60 shifted to lower frequency. These results imply a strong interfacial interaction and charge transfer from the Ag to the C60. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The intensity dependence of the transient photovoltaic response in the nanosecond region and the spectral dependence of the continuous wave (cw) photovoltaic response in Al/α-SnPc/ITO sandwich cell have been reported. The cw photovoltaic action spectrum is similar to the absorption spectrum. The magnitude, polarity, and response time of the transient photovoltage are found to be dependent on the intensity and wavelength of the incident light, which offers a potential application in the area of light-controlled nonlinear optoelectronic detectors. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Several strains of mice have been created which have reproductive defects secondary to disruption of the hypothalamic-pituitary-gonadal axis3,4. Although these mouse models are useful for studying reproductive function, many of these mice have multiple defects. For example, targeted disruption of ...
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A first-principles embedding theory that combines the salient features of density functional theory (DFT) and traditional quantum chemical methods is presented. The method involves constructing a DFT-based embedding potential and then using it as a one-electron operator within a very accurate ab initio calculation. We demonstrate how DFT calculations can be systematically improved via this procedure. The scheme is tested using two closed shell systems, a toy model Li2Mg2, and the experimentally well characterized CO/Cu(111) system. Our results are in good agreement with near full configuration interaction calculations in the former case and experimental adsorbate binding energies in the latter. This method provides the means to systematically include electron correlation in a local region of a condensed phase. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 3453-3458 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Depolarized low-frequency Raman spectra of aqueous electrolyte solutions (ACl and BCl2; A=Li, Na, K, Rb and B=Mg, Ca) in the frequency region from −250 to 250 cm−1 have been investigated over a wide concentration range. The spectra were analyzed with one Cole–Cole type relaxation mode and two damped harmonic oscillators. A broad relaxation mode was found below 20 cm−1. For the present aqueous electrolyte solutions, with increasing salt concentration each relaxation time τ becomes longer than that of liquid water τwater. The relaxation time is considered to correspond to the duration time of the tetrahedral structure of bulk water. We have found that the concentration dependence of the ratio τ/τwater is equivalent to the ratio η/ηwater, where η is the viscosity of aqueous solutions.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...