A Monte Carlo simulation of the Xe/Al(110) system has been performed i
n order to study the two-dimensional (2D) phase transition previously
detected by spectroscopic and diffraction experiments at temperature o
f 45 K and low submonolayer coverage, theta (Xe), of about 0.1 monolay
er. The simulation results suggest that the microscopic origin of this
structural transition is a change in the adsorption geometry of the a
datoms from 2D commensurate islands to incommensurate ones as a functi
on of Xe coverage. The shortening of the Xe-Xe distance in the incomme
nsurate structure agrees with LEED experiments on this system. These r
esults are in contradiction with the original suggestion, based on TDS
and UPS low coverage data, of a 2D-ps 2D-solid transition due to the
formation of Xe islands at T = 45 K and theta (Xe) = 0.1. We show that
a lattice-ps model predicts formation of Xe islands at Xe coverages m
uch lower than 0.1 monolayer at the studied temperature.