Wiener-type indices and internal molecular energy

In earlier studies it was established that internal molecular energies (Eint) of alkanes can be reproduced, in an approximate yet reliable manner, by means of a molecular-graph-based structure-descriptor U. It was also established that U is linearly correlated with the Wiener index W. We now show that the correlation between U and W is more complicated than earlier ex- pected, and that it cannot be represented by a single line. We also show that a very good linear correlation exists between U and a modified version Wm () of the Wiener index, which is thus more suitable for modeling Eint than the ordinary Wiener index.