234 research outputs found
Conditional constraint satisfaction and configuration: A win-win proposition
Over the years, a whole sector of AI dealing with configuration problems has emerged, and since 1996, an annual configuration workshop has been held in affiliation with a major AI conference. This installment of Trends & Controversies presents essays from the configuration workshop held in August 2006 as part of ECAI in Riva del Garda, Italy
Environment effects on effective magnetic exchange integrals and local spectroscopy of extended strongly correlated systems
The present work analyzes the importance of the different components of the
environment effects on the local spectroscopy of extended strongly correlated
systems. It has been found that the usual formal charge definition of the
charge transfer and Madelung potential are far too crude for an accurate
determination of the local excitation energies in embedded fragment
calculations. A criterion for the validation of the embedding against the
infinite system density of states has been proposed.Comment: 8 pages, 9 figure
Scattered one-counter languges have rank less than
A linear ordering is called context-free if it is the lexicographic ordering
of some context-free language and is called scattered if it has no dense
subordering. Each scattered ordering has an associated ordinal, called its
rank. It is known that scattered context-free (regular, resp.) orderings have
rank less than (, resp).
In this paper we confirm the conjecture that one-counter languages have rank
less than
Strong Coulomb effects in hole-doped Heisenberg chains
Substances such as the ``telephone number compound''
Sr14Cu24O41 are intrinsically hole-doped. The involved interplay of spin and
charge dynamics is a challenge for theory. In this article we propose to
describe hole-doped Heisenberg spin rings by means of complete numerical
diagonalization of a Heisenberg Hamiltonian that depends parametrically on hole
positions and includes the screened Coulomb interaction among the holes. It is
demonstrated that key observables like magnetic susceptibility, specific heat,
and inelastic neutron scattering cross section depend sensitively on the
dielectric constant of the screened Coulomb potential.Comment: 5 pages, 6 figures, to be published in Eur. Phys. J.
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