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Towards an order-N DFT method 总被引:5,自引:0,他引:5
C. Fonseca Guerra J. G. Snijders G. te Velde E. J. Baerends 《Theoretical chemistry accounts》1998,99(6):391-403
One of the most important steps in a Kohn-Sham (KS) type density functional theory calculation is the construction of the
matrix of the KS operator (the “Fock” matrix). It is desirable to develop an algorithm for this step that scales linearly
with system size. We discuss attempts to achieve linear scaling for the calculation of the matrix elements of the exchange-correlation
and Coulomb potentials within a particular implementation (the Amsterdam density functional, ADF, code) of the KS method.
In the ADF scheme the matrix elements are completely determined by 3D numerical integration, the value of the potentials in
each grid point being determined with the help of an auxiliary function representation of the electronic density. Nearly linear
scaling for building the total Fock matrix is demonstrated for systems of intermediate size (in the order of 1000 atoms).
For larger systems further development is desirable for the treatment of the Coulomb potential.
Received: 30 March 1998 / Accepted: 6 July 1998 / Published online: 15 September 1998 相似文献
3.
H. Ohshima 《Colloid and polymer science》1999,277(6):563-569
An exact analytical expression for the potential energy of the electrostatic interaction between a plate-like particle 1
and a cylindrical particle 2 of radius a
2 immersed in an electrolyte solution of Debye–Hückel parameter κ is derived on the basis of the linearized Poisson–Boltzmann
equation without recourse to Derjaguin's approximation. Both particles may have either constant surface potential or constant
surface charge density. In the limit of κa
2→0, in particular, the interaction between a plate with zero surface charge density and a cylinder having constant surface
charge density becomes identical to the usual image interaction between a line charge (a charged rod of infinitesimal thickness)
and an uncharged plate.
Received: 22 September 1998 Accepted in revised form: 27 January 1999 相似文献
4.
H. Reis S. Raptis M. G. Papadopoulos R. H. C. Janssen D. N. Theodorou R. W. Munn 《Theoretical chemistry accounts》1998,99(6):384-390
Starting from a set of high-level ab initio frequency-dependent molecular first- and third-order polarizabilities, the macroscopic
first-order (linear) and third-order (cubic) susceptibilities of the benzene crystal are calculated. Environmental effects
are taken into account using a rigorous local-field theory and are compared with the anisotropic Lorentz field factor approach.
The experimentally determined first-order susceptibility of crystalline benzene is accurately reproduced. Dispersion curves
for the first-order susceptibility and results for electric-field-induced second-harmonic generation and third-harmonic generation
experiments are predicted. Comparison with similar calculations conducted in the course of molecular simulations of liquid
benzene shows that the theoretical results for the two phases are of comparable accuracy. Overall, the results show that for
the fairly compact nonpolar benzene molecules, environmental effects on the effective molecular response are small.
Received: 11 February 1998 / Accepted: 6 July 1998 / Published online: 18 September 1998 相似文献
5.
Renato Colle Raffaele Montagnani Oriano Salvetti 《Theoretical chemistry accounts》1999,101(4):262-268
A molecular fragment approach is used to compute ionization potentials, transition energies and electron affinities of pyrrole
oligomers. The calculations of these quantities include correlation energy contributions evaluated by integrating a functional
of the two-particle Hartree-Fock density matrix. Pyrrole oligomers with chains of up to 16 rings are explicitly treated and
the calculated quantities extrapolated to the limit of an infinitely long chain, to predict polymer properties. The theoretical
results compare favorably with data on gas-phase ionization potentials deduced from experimental oxidation potentials, and
with optical absorption peaks recorded in solution or on solid films. The large discrepancy between electron affinities obtained
from the eigenvalues of an independent-particle frozen-orbital calculation and those obtained from separate, correlated calculations
on the neutral system and the negative ion in shown.
Received: 24 March 1998 / Accepted: 2 September 1998 / Published online: 7 December 1998 相似文献
6.
Following an approach to density functional theory calculations based on the matrix representation of operators, we implemented
a scheme as an alternative to traditional grid-based methods. These techniques allow integrals over exchange-correlation operators
to be evaluated through matrix manipulations. Both local and gradient-corrected functionals can be treated in a similar way.
After deriving all the required expressions, selected examples with various functionals are given.
Received: 7 March 1998 / Accepted: 21 May 1998 / Published on line: 6 August 1998 相似文献
7.
Thomas Luxbacher Harald P. Fritzer James P. Riehl Colin D. Flint 《Theoretical chemistry accounts》1999,103(2):105-108
The interaction between multipoles is not isotropic even in cubic systems. This results in the introduction of geometric
reduction factors in the calculation of energy-transfer rates in crystals. We derive these reduction factors for the cases
of dipole–dipole, dipole–quadrupole, and quadrupole–quadrupole couplings and present a general procedure for their derivation
in other cases. For the dipole–dipole case the geometric factor is independent of the distribution of the acceptor species,
but for higher-order couplings, a significant angular dependence is found.
Received: 6 November 1998 / Accepted: 15 January 1999 / Published online: 7 June 1999 相似文献
8.
Frank Jensen 《Theoretical chemistry accounts》1998,99(5):295-300
A total of 36 stationary points have been located on the H2CO potential energy surface by means of gradient extremal following. These 36 points are believed to represent all the important
stationary points on this surface. There is no indication that the structure of the surface becomes less complicated as the
size of the basis set is enlarged at the Hartree-Fock level of theory, but many of the second- and third-order saddle points
disappear when electron correlation is introduced. Of the ten first-order saddle points (transition structures) located, the
majority have reaction paths entering the associated minima in a side-on approach, i.e. these cannot be located by uphill
walking from the minimum.
Received: 5 February 1998 / Accepted: 21 May 1998 / Published online: 29 July 1998 相似文献
9.
In order to identify ineffective and, hence, superfluous configurations in algorithmically generated configuration spaces,
a direct configuration interaction (CI) method has been developed for determining completely general configurational expansions
based on arbitrary determinantal configuration lists. While based on the determinantal ordering scheme of Knowles and Handy,
our direct CI algorithm differs from previous ones by the use of the Slater–Condon expressions in direct conjunction with
single and double replacements. A full, as well as a completely general selected, CI program has been implemented. With it,
full configuration spaces of Ne, C2, CO and H2O with up to about 40 million determinants have been investigated. It has been found that, in all cases, fewer than 1% of
the configurations in a natural-orbital-based configuration expansion reproduce the exact results within chemical accuracy.
Received: 19 December 2000 / Accepted: 9 May 2001 / Published online: 11 October 2001 相似文献
10.
The conductor-like screening model (COSMO) of solvation has been implemented in the Amsterdam density functional program
with maximum flexibility in mind. Four cavity definitions have been incorporated. Several iterative schemes have been tested
for solving the COSMO equations. The biconjugate gradient method proves to be both robust and memory-conserving. The interaction
between the surface charges and the electron density may be calculated by integrating over either the fitted or exact density,
or by calculating the molecular potential. A disk-smearing algorithm is applied in the former case to avoid singularities.
Several self-consistent field/COSMO coupling schemes were examined in an attempt to reduce computational effort. A gradient-preserving
algorithm for removing outlying charge has been implemented. Preliminary optimized radii are given. Applications to the benzene
oxide-oxepin valence tautomerization and to glycine conformation are presented.
Received: 13 November 1998 / Accepted: 16 December 1998 / Published online: 16 March 1999 相似文献
11.
Hiroshi Nakatsuji 《Theoretical chemistry accounts》1999,102(1-6):97-104
The density equation proposed previously for the direct determination of the density matrix, i.e. for the wave mechanics
without wave, is extended to a time-dependent case. The time-dependent density equation has been shown to be equivalent to
the time-dependent Schr?dinger equation so long as the density matrix, included as a self-contained variable, is N-representable. Formally, it is obtainable from the previous time-independent equation by replacing the energy E with . The perturbation theory formulas for the density equation have also been given for both the time-dependent and time-independent
cases.
Received: 16 June 1998 / Accepted: 2 September 1998 / Published online: 8 February 1999 相似文献
12.
Substituent effects on the structure of radicals and parent hydrocarbons formed by isolated or condensed three-membered rings
have been investigated by Hartree-Fock, post-Hartree-Fock and density functional methods. The trends of structural parameters
computed for the hydrocarbon systems are in agreement with available experimental data. Substituent effects can be rationalized
in terms of interactions between localized orbitals obtained by natural bond analysis. The effects are even larger in free
radicals and can be analyzed using the same model.
Received: 13 March 1998 / Accepted: 13 July 1998 / Published online: 9 October 1998 相似文献
13.
A large-scale one-centre expansion with a radial B-spline basis set is implemented for bound and continuum states. A Kohn-Sham
hamiltonian is employed with Hartree and exchange-correlation potentials calculated from the SCF electron density taken from
a previous LCAO calculation. An inverse iteration method is used to obtain the continuum wavefunction, from which the cross
section and asymmetry parameter are calculated. The convergence with respect to angular momentum and cut-off radius is analysed
for N2. The relevance of multipolar contributions even at large distances is shown and suggestions for further improvements are
given. In order to show that the present method is suitable to treat systems of moderate size, the (CH3)3N molecule has also been calculated and the results are compared with experiment.
Received: 19 May 1998 / Accepted: 20 August 1998 / Published online: 7 December 1998 相似文献
14.
Jenn-Kang Hwang 《Theoretical chemistry accounts》1999,101(5):359-363
The Monte Carlo Fourier path integral approach has proved to be quite useful in calculating equilibrium thermodynamic properties.
One of its advantages is that it can be formulated in such a way as to include higher order terms using the partial averaging
technique, which includes the contribution from higher terms usually neglected by the discretized path integral approach.
In the original approach, the Feynman path integral is evaluated via a free-particle reference state. Here, using a new expression
for the Feynman paths expanded around a harmonic reference path, we derive an alternative formulation for the density matrix
element and its corresponding partial averaging expression.
Received: 16 September 1998 / Accepted: 30 October 1998 / Published online: 1 February 1999 相似文献
15.
Seiichiro Ten-no Suehiro Iwata Sourav Pal Debashis Mukherjee 《Theoretical chemistry accounts》1999,102(1-6):252-261
Employing separate cluster ansatz in time-independent and time-dependent wave-operators, coupled-cluster (CC) response theory
is generalized to multireference (MR) expansion spaces. For state energies, this corresponds to the MR secular problem with
an arbitrary similarity-transformed effective Hamiltonian, H˜=Ω−1
HΩ. The effective Hamiltonian can be generated via size-extensive CC methods. Thus the states in MR linear response theory
(MRLRT) maintain the usual CC core-extensive properties. We have used the Gelfand unitary group basis of the spin-adapted
configurations to construct the matrix of H˜ in the MR excitation space. As a preliminary application, the CC singles and
doubles effective Hamiltonian is applied to excitation and photoionization energies of the CH+ and N2 molecules, and is compared with experimental results and results from other numerical procedures including conventional CC
linear response theory (CC-LRT), MR and full configuration interaction (MRCI and FCI) methods. The numerical results indicate
that MRLRT reproduces valence and external excited states quantitatively, combining the best features of CC-LRT and MRCI.
Received: 2 July 1998 / Accepted: 28 August 1998 / Published online: 11 November 1998 相似文献
16.
J. Andrés M. Oliva V. S. Safont V. Moliner O. Tapia 《Theoretical chemistry accounts》1999,101(1-3):234-240
The carboxylation and oxygenation processes of a model substrate, 3,4-dihydroxy-2-pentanone, have been theoreticaly characterized
as a set of steps, mimicking the corresponding reactions of D-ribulose-1,5-bisphosphate catalyzed by rubisco. A theoretical characterization is carried out of transition-state structures
and possible molecular intermediates represented as saddle points of index 1 and minimum energy structures, respectively.
The quantum chemical characterization, at the HF/3-21G calculation level, of these stationary points is used to rationalize
and to discuss both catalyzed sequences. The reported set of these stationary points maps out most experimental aspects of
the reaction pathways for the real system.
Received: 24 March 1998 / Accepted: 3 September 1998 / Published online: 10 December 1998 相似文献
17.
Sanna Jääskeläinen Chandra S. Verma Roderick E. Hubbard Leo S. D. Caves 《Theoretical chemistry accounts》1999,101(1-3):175-179
The conformational change associated with the interfacial activation of Rhizomucor miehei lipase involves the displacement of an α-helical lid (residues 82–96) away from the active site on moving from water (high
dielectric) to lipid (low dielectric). The presence of two media of very different dielectric properties suggests that electrostatic
interactions play an important role in this process. We have used linearized Poisson–Boltzmann calculations to examine the
key electrostatic interactions which contribute to lid stability in the closed and open states. It is the two charged residues
of the lid, Arg86 and Asp91, that form the strongest electrostatic interactions with the rest of the protein. We identify
key residues whose interactions with the lid are significantly perturbed by the change in the dielectric of the medium: Asp61,
Arg80, Lys109, Glu117 and the active-site residues Asp203 and Asp256, all of which lie within approximately 20 ? of the lid.
We suggest that these residues are good candidates for site-specific mutation studies, which could help elucidate their role
in the lipase activation mechanism.
Received: 27 May 1998 / Accepted: 17 September 1998 / Published online: 7 December 1998 相似文献
18.
W. R. Fahrner G. Grabosch D. Borchert Y. Chan S. Kwong K. Man 《Journal of Solid State Electrochemistry》1999,3(5):245-250
The admittance versus frequency of a hydrogenated amorphous silicon metal oxide semiconductor capacitor is measured at a
fixed bias in inversion and for temperatures in the range of 20–50 °C. The data are fitted to theoretical capacitance and
conductance curves where the time constant of inversion is the result of the fit. In turn, the time constant can be converted
to the (minority) carrier lifetime so that a lifetime value for each measurement temperature is available. The conversion
from the time constant to the minority carrier lifetime requires the knowledge of the temperature-dependent intrinsic carrier
density or rather its activation energy. The criterion for the correct choice is a temperature-independent carrier lifetime.
Three published room temperature values of the intrinsic carrier density have been tested. The carrier lifetime activation
energy is E
a = 0.70 ± 0.03 eV.
Received: 17 June 1998 / Accepted: 23 October 1998 相似文献
19.
The ground state of the van der Waals-type lanthanide dimer Yb2 has been studied by means of relativistic energy-consistent ab initio pseudopotentials using three different core definitions.
Electron correlation was treated by coupled-cluster theory, whereby core-valence correlation effects have been accounted for
either explicitly by correlating the energetically highest coreorbitals or implicitly by means of an effective core-polarization
potential. Results for the first and second atomic ionization potentials, the atomic dipole polarizability, and the spectroscopic
constants of the molecular ground state are reported. Low-lying excited states have been investigated with spin-orbit configuration
interaction calculations. It is also demonstrated for the whole lanthanide series that correlation effects due to the atomic-like,
possibly open 4f-shell in lanthanides can be modeled effectively by adding a core-polarization potential to pseudopotentials attributing the
4f-shell to the core.
Received: 3 April 1998 / Accepted: 27 July 1998 / Published online: 9 October 1998 相似文献
20.
G. N. K. Ramesh Bapu G. Devaraj J. Ayyapparaj 《Journal of Solid State Electrochemistry》1998,3(1):48-51
An alkaline non-cyanide zinc plating solution consisting of 10 g/l zinc oxide, 90 g/l sodium hydroxide and 1.5 g/l gelatine
was prepared . Using this solution, a smooth, uniform and fine-grained semi-bright deposit was obtained on mild steel sheets
over a wide range of current density and pH at 303 K. The plating bath had about 63% current efficiency and 25% throwing power
at 303 K and at pH 10. Caffeine and vanillin additions to this bath gave bright zinc deposits.
Received: 30 January 1998 / Accepted: 15 May 1998 相似文献