  We report a method using scanning tunnelling microscope single molecular
break junction to simultaneously measure and correlate the single-molecule
thermopower and electrical conductance. In contrast to previously reported
approaches, it does not require custom-built electronics and takes advantage of
a trace-by-trace calibration of the thermal offset at the Au/Au contact, thus
greatly facilitating thermoelectric measurements at the single-molecule level.
We report measurements of three molecules:
1,4-di(4-(ethynyl(phenylthioacetate)) benzene, 1,8-octanedithiol, and
4,4'-bipyridine, and determine single-molecule Seebeck coefficients of 12(3),
5(2), and -5(2) microV K-1, respectively. Furthermore, the method statistically
correlates the Seebeck voltage offset, electrical conductance, and stretching
displacement of the single-molecule junction, and allows for direct comparison
with current-distance spectroscopy results obtained at constant bias.
