Journal of Computational Chemistry最新文献

We present a benchmark set LIMIXCARB_RE12 comprising 12 reference DLPNO-CCSD(T₁)/CPS(6,7)/CBS(cc-pwCVTZ/cc-pwCVQZ)//PBE0-D3(BJ)/def2-TZVP binding energies for the sizeable (up to 69 atoms) clusters of Li⁺ ion with mixed cyclic and linear organic carbonates. A number of computationally cheaper DLPNO-CCSD(T)-based Feller-Peterson-Dixon protocols including contributions due to core-valence electron correlation, using more accurate iterative triples correction (T₁) and tighter-than-default PNO settings are examined with respect to their accuracy and efficiency. Particular splittings of the total binding energy into components allow maintaining high accuracy (deviations less than 0.2 kcal mol⁻¹) at significantly reduced computational cost. Much faster convergence of the DLPNO-CCSD(T) binding energies to the reference values is reached if Ahlrichs' def2 basis sets are used instead of their correlation-consistent Dunning counterparts. Evaluation of the DFT approximations against the LIMIXCARB_RE12 reveals double hybrid PWPB95-D4 in conjunction with CBS(def2-TZVPP/def2-QZVPP) extrapolation to be the best performer with mean signed deviation (MSD) of only −0.1 kcal mol⁻¹ followed by r²SCAN-D4/D3(BJ) and r²SCAN-3c (MSD < 1 kcal mol⁻¹), while hybrid B3LYP and PBE0 functionals complemented with D3(BJ) or D4 dispersion corrections are clearly inferior. The obtained results provide a guide for the accurate calculations of the binding energies of the microsolvated clusters and can be used for the development and validation of the emerging computational methods.

Small hydrocarbons are central to astrochemistry due to their prevalence and chemical reactivity across diverse interstellar environments. Here, we present HydroMol, an open-access computational platform designed for systematic exploration and analysis of hydrocarbon chemical spaces, featuring over 2700 neutral $��{�\text{C}�}_{�n�}�{�\text{H}�}_{�m�}�(�n�,�m�=�1�-�10�)�$ hydrocarbon structures generated stochastically and refined via density functional theory at B3LYP-D3BJ/def2-SVP level. HydroMol provides detailed molecular geometries, thermodynamic parameters, and electronic properties critical for interpreting astrochemical phenomena and identifying promising observational targets. Our database, hosted within a lightweight client-side web application for rapid search and visualization, introduces approximately 2000 previously unreported hydrocarbons absent in major chemical repositories such as PubChem. Statistical analysis highlights the predominance of structurally simple monocyclic and bicyclic species, characterized by HOMO and LUMO energies centered at approximately $��-�6�$ and $��-�2�$ eV, respectively, and typical HOMO–LUMO gaps around 4–5 eV. The methodology is readily extendable to heavier elements and expanded property datasets, providing a valuable resource for astrochemical modeling, molecular spectroscopy, and computational hydrocarbon discovery. The HydroMol web application is freely accessible at https://hydromol.github.io.

Phenalenyl is known for its highly delocalized radical structure, making it a fundamental building block in the construction of polyradical compounds. This study explores how different connection topologies between phenalenyl units via acetylenic bridges modulate the polyradical character, as well as the electronic and magnetic properties of the resulting systems. The connection type depends on the atom occupation pattern of the phenalenyl singly occupied orbital (SOMO). Three types of connections are defined that induce different π conjugation strength. Linear di- and tetra-phenalenyl chains and cyclic tri- and tetra-phenalenyl aggregates have been investigated. High-level multireference averaged coupled cluster (MR-AQCC) calculations were performed to describe the electronic structures of these compounds. The polyradical character of the oligomers is assessed using descriptors such as singlet-triplet splitting, effectively unpaired electrons (N_U). Additionally, the harmonic oscillator model of aromaticity (HOMA), multicenter index (MCI), fluctuation index (FLU), nucleus-independent chemical shifts (NICS (1)), and the anisotropy of the current-induced density (ACID) analysis are employed to characterize the influence of the phenalenyl linkages on aromaticity. Results indicate that bridges enabling stronger interaction between the SOMOs of phenalenyl units lead to a reduction in polyradical character. Aromaticity analysis corroborates these findings, revealing decreased aromaticity in rings where electron interaction occurs through the bridge. On the contrary, choosing bridging types of weak interaction leads to strong open shell character providing candidates for molecular magnetism. A comparison with the predictions of Ovchinnikov's rule is carried out both to rationalize the outcomes of the quantum chemical calculations and to highlight limitations of the rule, particularly in the treatment of quasi-degenerate states.

In this research, K₂AlInZ₆ (Z = F, Cl, Br) are double perovskite compounds with unique and complementary characteristics, rendering them exceptionally appropriate for many modern technological applications. This paper provides a thorough examination of the structural, electronic, elastic, mechanical, optical, and thermodynamic features of K₂AlInZ₆ (Z = F, Cl, Br) double perovskites by first-principles calculations based on density functional theory (DFT). The structural characteristics, encompassing lattice parameters and formation energies, validate the stability of these materials, which exhibit a cubic configuration with the Fm-3m space group. The electronic band structure calculations with the modified Becke-Johnson exchange potential indicate indirect band gaps for K₂AlInZ₆ (Z = F, Cl, Br), with band gaps of 3.73, 2.88, and 2.41 eV for K₂AlInF₆, K₂AlInCl₆, and K₂AlInBr₆, respectively, rendering them viable candidates for optoelectronic applications. The estimated elastic constants, bulk modulus, and shear modulus demonstrate mechanical stability, indicating their suitability for durable and flexible devices. The optical characteristics, including dielectric functions and absorption spectra, exhibit considerable absorption in the ultraviolet range, indicating their potential use in photovoltaic systems. Furthermore, the thermodynamic characteristics are examined by assessing formation energy and Debye temperature. The negative formation energies of these materials signify their strong thermodynamic stability, whereas the Debye temperature analysis elucidates their lattice vibrations and heat capacity, further substantiating their stability and applicability in diverse energy technologies. At 800 K, K₂AlInF₆, K₂AlInCl₆, and K₂AlInBr₆ show Seebeck coefficients of ~150, ~160, and ~135 μV/K, respectively, with κ_e/τ rising to ~4.0–4.75 × 10¹⁴ W/mKs. ZT values peak at ~0.69, ~0.68, and ~0.58, indicating strong thermoelectric potential at high temperatures.