The HOMA index reflects a more general property of cyclic hydrocarbons then aromaticity: the savoricity.

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The HOMA index can be useful for acyclic linear systems and design of new conducting polymers.

To measure molecular chirality, the molecule is treated as a finite set of points in the Euclidean R(3) space supplemented by k properties, p(1)((i)), p(2)((i)), ..., p(k)((i)) assigned to the ith atom, which constitute a point in the Property P(k) space. Chirality measures are described as the distance between a molecule and its mirror image minimized over all its arbitrary orientation-preserving isometries in the R(3) × P(k) Cartesian product space. Following this formalism, different chirality measures can be estimated by taking into consideration different sets of atomic properties. Here, for α-amino acid zwitterionic structures taken from the Cambridge Structural Database and for all 1684 neutral conformers of 19 biogenic α-amino acid molecules, except glycine and cystine, found at the B3LYP/6-31G** level, chirality measures have been calculated by a CHIMEA program written in this project. It is demonstrated that there is a significant correlation between the measures determined for the α-amino acid zwitterions in crystals and the neutral forms in the gas phase. Performance of the studied chirality measures with changes of the basis set and computation method was also checked. An exemplary quantitative structure–activity relationship (QSAR) application of the chirality measures was presented by an introductory model for the benchmark Cramer data set of steroidal ligands of the sex-hormone binding globulin.

Eleven exchange-correlational functionals of different types corrected for dispersion by Grimme's D3 correction in conjunction with the aug-cc-pVTZ basis set were tested on the following noble gas (Ng) dimers: Ne 2 , Ar 2 , Kr 2 , Xe 2 , and Rn 2 . For comparison, the D2 and D3BJ corrections were probed with the B3LYP functional. From post-HF wavefunction methods, CCSD(T) theory was also included. The investigated properties involved potential energy curves, equilibrium bond distances, and interaction energies. The B3LYP-D3, B3LYP-D3BJ, and PBE0-D3 functionals performed overall best for bond distances, while B3LYP-D3 and B97-D3 performed best for interaction energies. The importance of fortunate error cancellations was seen in the often reduced agreement with reference data upon correction for BSSE. As several functionals performed well selectively for some noble gases (and poorly for others), we also analysed the performance on the Ng 2 dimers individually and recommended DFT-D3 functionals for the calculation of large clusters of each Ng.benchmark, bond distance, DFT-D3, interaction energy, noble gas dimers | I N T R O D U C T I O NLow-temperature matrix isolation is a powerful tool for the study of molecular properties of species unstable under normal conditions, such as single molecules, radicals, molecular complexes, [1,2] or hardly vaporizing metal oxides. [3,4] The technique is based on the co-deposition of a noble gas (Ng) or another relatively inert gas together with the studied compound onto a cold window or a capillary tube placed in a cryostat, which enables spectroscopic measurements at temperatures as low as 5 K. The majority of such matrix-isolation measurements are combined with IR, UV-Vis, luminescence, and ESR techniques, [1,2] and less frequently with Raman, [5][6][7] M€ ossbauer, [8,9] and VCD. [10][11][12] Effective isolation that prevents intermolecular interactions between the studied species and changes in the physical states of interest is assured by a large excess (ca. 1000-fold) of the matrix gas with respect to the number of captured molecules. Among Ng-s applied in the matrix isolation technique, Ar and Kr are the most frequently used. He is not suitable for conventional matrix-isolation experiments due to its very low (ca. 1 K) melting point.The melting point of Ne is about 25 K, which is unfavorably low for annealing experiments, while Xe introduces strong interaction effects and, in extreme cases, may even react with the captured molecule. The latter unfavorable effects are even more prominent when using Rn, to say nothing of the hazards resulting from its radioactivity.Although contact between the captured molecules is avoided, their interaction with the matrix cannot be prevented. The matrix produces only a very weak perturbation of the states of the captured species.Amongst them, the interactions are weakest with Ne and increase along with the polarizability of the Ng, which is related to its atomic size. The matrix-guest interactions are most clearly manifested in band...

The stability of all 23 C(58)N(2) and C(58)B(2) heterofullerenes in the singlet and triplet states was determined at the B3LYP/6-31G** level. In equilibrium mixture the achiral (1,4) C(58)N(2) isomer would be populated in ca. 95.8%, the chiral (1,16) one in ca. 3.3%, and the achiral (1,4) C(58)B(2) in 100%, whereas all triplet state isomers are less stable. Fourteen out of 23 C(58)X(2) are chiral. Four different chirality measures were calculated by our own CHIMEA program: pure geometrical, labeled, mass, and charge. Intercorrelations between the measures for all chiral compounds indicate that the pure geometrical chirality measure is unstable and should not be used in QSAR predictions of the other molecular properties, while the labeled and mass-weighted ones are promising QSAR descriptors. For each chiral C(58)N(2) molecule, some very strong VCD bands, of intensity comparable with that in the IR spectra, can serve in identification and characterization of the isomers.

To understand interactions between astatine atoms with gold clusters the AunAt and AunX clusters, n = 12 or 13, X = F, Cl, Br, and I, were calculated at the DFT level using basis sets with a quasi-relativistic pseudopotential.

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