Super-descriptors

The observed vs. calculated plots have been obtained with the given correlation vector C of the optimal descriptor of Table 7.9 (unless otherwise stated). The derivation of the semi-random descriptors, due to the limits of the our PC, could not be searched with the two sets of random indices plus all MC indices plus the five experimental parameter and M. They have been calculated in a more compact way, which is explained in each property s paragraph. The super-descriptors have been obtained with a full search over the set of indices of the optimal descriptors for the 12 properties (see the corresponding paragraph). 

All different MC or empirical indices of the full normal (non semi-random) descriptors of Tables 7.9 and 7.10 are now joined together to form a new space of indices, kind of super-indices, which will be used for a full combinatorial search of the best super-descriptors in a kind of configuration interaction of best indices. This super-descriptor space gave no remarkable results with the greedy algorithm, but it does find improved descriptions for the following four properties. 

The search of a seven-index semi-random super-descriptor with rl-r38 or rdl-rd38 plus the super-indices is beyond the power of our PC. A search for a seven-index... 

No better super-descriptor is here found, but the search throughout a combinatorial space made of the 32 super-indices plus the rl-rS8 and then rdl-rdS8 finds a five-index mc-exp-m-super-descriptor, which improves slightly in i and q over the previous semi-random descriptor,... 

Excluding the four strong outliers, heptane, 4-Me-2-pentanone, NNJ-diMe-acetamide, and acetonitrile, the following unproved super-descriptor can be found... 

The entire combinatorial space made of RI, AP/, the 32 super-indices plus the rl-r38 and then rdl-rd38 random sets has been searched and no interesting results have been found. The given five-index super-descriptor is by far the best descriptor. The search with the five indices of the previous descriptor plus the two sets of random indices finds also no different descriptor. The search with the first four... 

No best super-descriptor can be found (remind no acetonitrile ). Instead, a quite good semi-random super-descriptor is found by the aid of a search with a space made of -super-indices (inclusive (f)e and (j>M) plus and then (j)rdl-(l)... 

Table 3) with seven-, five-, three-, and two-index index super-descriptor to keep an eye to the importance of the Topliss-Costello rule. In the following lines are the results,... 

In the following is the best model of the randomized properties with rl-r38 and rdl-rd38 random numbers. The quality of this seven-random-index descriptor is not far from the quality of the previous seven index super-descriptor, especially at the level,... 

The advantage to work with indices belonging to different configurations is emphasized by possibility to derive super-descriptors (Sd) for model purposes, i.e., combinations of indices of the best descriptors (super-indices) of the 12 properties in a kind of configuration interaction procedure performed with the full combinatorial algorithm. Super-descriptors are, in fact, able to consistently improve the model of T , and, a bit less consistently, to improve the model of FP and ji. 

Quantum chemical descriptors such as atomic charges, HOMO and LUMO energies, HOMO and LUMO orbital energy differences, atom-atom polarizabilities, super-delocalizabilities, molecular polarizabilities, dipole moments, and energies sucb as the beat of formation, ionization potential, electron affinity, and energy of protonation are applicable in QSAR/QSPR studies. A review is given by Karelson et al. [45]. 

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