Showing papers in "Chemical Physics Letters in 1997"

TL;DR: In this article, the authors investigated the possibility of fast and sufficiently accurate evaluation of Coulomb and exchange correlation terms using the expansion of molecular electronic density in atom-centered auxiliary basis sets, which is shown to be about an order of magnitude faster than usual approaches in which only Coulomb terms are treated using the approximated density.

TL;DR: The numerical effectiveness of a new algorithm, parallel tempering, is studied for numerical simulations of biological molecules that suffer from a rough energy landscape and is comparable to sophisticated methods like generalized ensemble techniques.

TL;DR: In this paper, a new method for dividing a crystalline electron distribution into molecular fragments is proposed, based on Hirshfeld's partitioning scheme, which partitions the crystal into smooth molecular volumes as well as intermolecular voids of low electron density.

TL;DR: In this paper, it was found that the results of B3LYP calculations are not consistent throughout different implementations of this HF/DFT hybrid functional and the origin of this discrepancy lies in the two different formulations of the VWN local correlation functional, and it depends on the program which one is incorporated in the B3lyP functional.

TL;DR: In this paper, a density functional for short-range electron-electron interaction was implemented into a multi-reference configuration-interaction code with explicit treatment of long-range interaction only, using as examples some closed-shell atoms (Be, Ne) and diatomics (H2, Li2, C2, N2, F2).

TL;DR: In this paper, the authors proposed an alternative which may be regarded as an imaginary shift, where the singularities are not moved, but disappear completely, replaced by a small distortion of the potential function.

TL;DR: In this paper, the Hartree-Fock and density functional exchange is determined a priori from purely theoretical considerations and no further parameters are present, and the numerical results obtained on a standard molecular data set and on some ‘delicate’ chemical systems indicate that this model has essentially the same performance as the B3LYP model, but within a more satisfactory theoretical framework.

TL;DR: In this article, the authors demonstrate the use of an auxiliary basis set expansion for the treatment of Coulomb type matrix elements in time-dependent density functional (TDDFT) calculations.

TL;DR: In this paper, the authors demonstrate that a commercial single-frequency cavity ring down spectroscopy (CRDS) can also be conveniently employed, allowing to gain in spectral resolution, signal intensity and data acquisition rate.

TL;DR: In this paper, a computer-controlled acousto-optic pulse shaper and a genetic algorithm were used to optimize population transfer from ground to first excited state in a molecular system.

TL;DR: The CCSD(T) method was originally motivated as an attempt to treat the effects of triply excited determinants upon both single and double excitation operators on an equal footing as mentioned in this paper.

TL;DR: Femtosecond transient absorption measurements of the photoisomerization of azobenzene excited at 435 nm in the long-wavelength formation with a dominating 170 fs and a weak 2 ps component are found.

TL;DR: In this article, it was shown that pyrolysis of metallocenes such as ferrocene, cobaltocene and nickelocene yields carbon nanotubes and metal-filled onion-like structures.

TL;DR: An ab initio calculation of the infrared spectrum of liquid water has been performed using Car-Parrinello molecular dynamics and evaluating the electronic polarization by means of the Berry phase formulation as mentioned in this paper.

TL;DR: In this paper, a general-purpose implementation of analytic CCSD(T) second derivatives is presented, which is demonstrated by calculations of vibration-rotation interaction constants for the astrophysically important molecule cyclopropenylidene (C3H2).

TL;DR: In this article, a density functional tight-binding study of boron-nitrogen polyhedra (BN) x composed entirely of four-and six-membered rings was performed and it was predicted that octahedron-like structures B 12 N 12, B 16 N 16 and B 28 N 28 are magic structures.

TL;DR: In this paper, a new structure of dye-sensitized nanocrystalline photoelectrochemical cell, which permits effective absorption of incident solar energy using thinner dye sensitized film, is proposed based on theoretical examination.

TL;DR: In this paper, a simple hybrid of generalized gradient approximations with the exact exchange energy is derived which improves the GGA result for systems in which GGA works better for exchange-correlation energies than for exchange alone.

TL;DR: In this paper, it is shown that the standard binning method utilized in the classical study of scattering processes dealing with more than three atoms, which consists in rounding the product vibrational actions (the x i's) to their nearest (the n i ''s), is not appropriate when the total energy disposal in the products is too low for the classical and quantum densities of vibrational states to be equal.

TL;DR: In this article, a CW single frequency dye laser was used in place of the pulsed laser of standard CRDS to obtain high quality NO2 spectra in a supersonic slit jet, with a residual Doppler width of about 250 MHz.

TL;DR: In this paper, the first single-molecule electromechanical amplifier is described, the active element of which is one fullerene molecule with a junction length and width of ∼ 1 nm and forces in the nano-Newton range are generated by a metallic tip pressing on the molecule in its adsorbed state.

TL;DR: In this article, a two-step reaction scheme was employed for the synthesis of SiC nanorods at 1400°C, where SiO vapour was generated via the silicon reduction of silica, and then this SiO vapor reacted with carbon nanotubes to form SiC norods.

TL;DR: In this paper, the counterpoise correction method of Boys and Bernardi is generalized for a consistent treatment of the basis set superposition error (BSSE) of three-body and higher many-body effects along the line used by White and Davidson for the three body terms in an ice model.

TL;DR: In this paper, small clusters of iron, cobalt, and nickel were studied with all-electron density functional calculations using both local and generalized gradient approximations, yielding structures where the bonding is maximized but high magnetic moments still remain, coupled ferromagneticically.

TL;DR: In this paper, a systematic exploration of the growth of Au clusters has revealed a critical size for the formation of stable assemblies, and the precise identities of this sequence of special structures can now be sought.

TL;DR: In this paper, a genetic algorithm was used to solve a crystal structure solution from powder diffraction data in the case of ortho-thymotic acid, and the structure solution was found efficiently in the genetic algorithm calculation, and was then used as the initial structural model in Rietveld refinement calculations.

TL;DR: In this article, a near-infrared luminescent ytterbium (III), neodymium(III) and erbium-III chelates containing organic chromophores derived from fluorescein and eosin have been synthesized and studied spectroscopically.

TL;DR: In this paper, the growth mechanism of the heterogeneous nanotubes is discussed and a growth model for the growth of the nanotubes is discussed in terms of electron microscopy and electron energy loss spectroscopy.

TL;DR: The infrared spectra of gas-phase uracil, thymine, and adenine have been recorded from 100 to 3700 cm−1 at a resolution of 1 cm −1 as mentioned in this paper.

TL;DR: In this paper, high-yield single wall nanotubes (SWNT) material consisting primarily of zero-helicity armchair tubes was annealed at 1400 or 1500°C under medium-high vacuum, flowing argon and flowing hydrogen atmospheres.