  We describe the existence of local distortion discovered in the synchrotron
x-ray single-crystal structure analysis of layered ditelluride 1T-MTe2 (M = V,
Nb, Ta). In 1T-TaTe2, the double zigzag chain structure of Ta is deformed at
about 170 K, and heptamer molecules are formed periodically at low
temperatures. We found that some of the Ta atoms that compose the double zigzag
chain structure appearing at high temperatures are locally displaced, resulting
in local dimerization. This tendency weakens when Ta is replaced by V or Nb.
Our results indicate that the local distortion persistently survives in these
ditellurides, where the electronic degrees of freedom, including orbitals, are
weakened. We further discuss the origin of local distortion in these
ditellurides, which is different from many usual material systems where
molecular formation occurs at low temperatures.
