  We present Synchrotron XRD measurements on powdered single crystal samples of
BaFe2-xRuxAs2 samples, as a function of Ru content at room temperature. The
Rietveld refinements reveal that the a-axis increases with Ru substitution,
while the c-axis decreases. The variation of positional co-ordinates of As
(zAs), the Fe-As bond length and the As-Fe-As bond angles have been determined
from the Rietveld refinements. In the sample with x=0.1, temperature dependent
XRD measurements were carried out. The results indicate that while the
orthorhombicity shows the characteristic increase with decrease in temperature,
the As-Fe-As bond angles, Fe-As bond length and positional co-ordinate of the
As show definite anomalies close to the structural transition. First principle
ab-initio simulations are performed in order to understand the experimentally
observed anomalies in structural parameters. The experimental observations are
discussed in the context of the simulation results.
