Structural models obtained using classical molecular dynamics (MD)
simulations and realistic interatomic potentials for solid metals
are tested using experimental results obtained by x-ray absorption
spectroscopy (XAS). Accurate L-edge
extended x-ray absorption fine-structure (EXAFS) measurements of Pb
grains dispersed in BN and graphite matrices have been collected for
temperatures up to the melting point. The thermal expansion of the
grains was measured by energy-dispersive x-ray diffraction
techniques and found to be coincident with that of pure Pb up to the
limit of the present measurements. L3-edge EXAFS
measurements of solid Pb at various temperatures have been analysed
using advanced data-analysis techniques (GNXAS)
based on exact spherical-wave multiple-scattering simulation of the
absorption cross-section. Realistic structural models for solid Pb
were obtained from MD simulations using an empirical pair potential
(Dzugutov, Larsson and Ebbsjo (DLE)), a tight-binding (TB)
square-root functional, and an
embedded-atom (EA) model potential parametrized by us. The
short-range pair distribution function g(r) reconstructed by means
of EXAFS is compared with those obtained by MD simulations. The
empirical DLE potential, originally designed for the liquid state,
is too soft, showing too-large values for the average distance R,
variance σ2, and skewness β. The TB and EA potentials
are both compatible with XAS data as regards the average distance
and skewness of the first neighbours. The distance variance,
associated with the thermal vibration amplitudes, is underestimated
for the TB potential, while the EA model is found to be in agreement
with XAS data. The present results are also compared with those
from a previous EXAFS study on solid lead, where the cumulant
expansion and a simple one-dimensional anharmonic oscillator model
were used. The need for realistic interaction models and
appropriate simulation schemes for reliable XAS data analysis is
emphasized, while differences from and improvements with respect to
previous approaches are only briefly discussed.