Soft-mode anisotropy in the negative thermal expansion material <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>ReO</mml:mi></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:math>

We use a symmetry-motivated approach to analyze neutron pair distribution function data investigate the character of soft phonon modes in negative thermal expansion (NTE) material ${\mathrm{ReO}}_{3}$. This analysis shows that its local structure is dominated by an in-phase octahedral tilting mode and units are far less flexible scissoring-type deformations than related NTE compound ${\mathrm{ScF}}_{3}$. The lack flexibility ${\mathrm{ReO}}_{3}$ restricts NTE-driving phonons smaller region reciprocal space, limiting magnitude temperature range NTE. These results support idea structural important factor materials. Surprisingly, our show fluctuations, even at elevated temperatures, respect symmetry order parameter direction initial pressure-induced phase transition result indicates dynamic motions associated with rigid unit highly anisotropic these systems.