EL: the new aromaticity measure based on one-electron density function

Ellipticity of the bond, being the quantity which numerically reflects how far the given chemical bond has elliptic cross-section, may be used to estimate pi-electron contribution in bonding. We make use of that fact and develop a new measure of aromaticity-EL index. Since ellipticity is available from calculations on one-electron density function, EL can be used for both theoretical and experimental data. The EL measure is normalized to make interpretation of this parameter as easy and comfortable as possible. We compare EL values with the values of other commonly used aromaticity measures, such as HOMA, PDI, FLU, and NICS. It appears that the indications of EL are in agreement with indications of other indices and general expectations.