In the present study we explored the effects of the basis set and theoretical molecular weight calculator level on toluene as a test case. Table 1 reports the ��, ����, and ��vec values of toluene calculated using the CAM-B3LYP and MP2 levels with the 6-31+G* and Sadlej’s POL basis set. The latter basis set was specifically constructed for polarizability computations and has been recently employed with success to predict the electronic polarizabilities of naphthalene (N) [68]. However, it is well-demonstrated that for ��-conjugated compounds the smaller 6-31+G* basis set furnishes an adequate alternative to the POL as well as more extended basis sets for predicting response electric properties, but at significantly minor computational costs [39, 45�C48, 52�C54].Table 1Static electronic �� (?3), ���� (?3), and ��vec (10?53C3m3J?2) of toluenea.

The present results show that when passing from the 6-31+G* to the POL basis set, only marginal effects are observed. In fact, the �� and ���� values increase by 0.75?3 (+6.5%) and 0.25?3 (+3.9%), respectively, whereas the ��vec decreases by 37.3 �� 10?53C3m3J?2 (?13.3%). Note that the (hyper)polarizability calculations carried out using the 6-31+G* basis set require noticeably minor CPU resources than those with the POL basis set (by about a factor of twenty!). In addition, we investigated the effects of the computational method, by comparing the CAM-B3LYP and MP2 (hyper)polarizability data. In line with the recent literature [37�C39, 45�C48, 69], the differences between the two levels are further smaller than those found for the basis sets, the ��, ����, and ��vec values being calculated within 0.

07?3 (0.6%), 0.19?3 (3.0%), and 4.2 �� 10?53C3m3J?2 (1.3%), respectively. Thus, considering the above results, the CAM-B3LYP/6-31+G* level can be judged as an acceptable compromise between accuracy and computational cost and has been entirely employed for the subsequent calculations on the static and frequency-dependent (hyper)polarizabilities of the DMN isomers. 3.2. Static and Dynamic Polarizabilities of the DMN IsomersTable 2 lists the static and frequency-dependent polarizabilities of the DMNs calculated in the gas phase at the CAM-B3LYP/6-31+G* level. For all the isomers, ��xx is the largest component, giving 43�C49% of the total polarizabilities (��xx + ��yy + ��zz). The dispersion effects here evaluated at the �� = 0.04282a.u.

are rather modest, increasing the static ��xx, �� and ���� values by 0.54�C0.70?3 + (2%), 0.34�C0.36?3 (+2%) and 0.40�C0.55?3 (+3%), respectively. Table 2 also reports the data of the unsubstituted compound N for which some experimental and high-level correlated ab initio values are available in the literature [68, 70]. The static CAM-B3LYP/6-31+G*��xx, �� and ���� values of N agree AV-951 satisfactorily with both the observed (within ?0.8, ?2.8, and +2.3%, resp.