Journal of Computational Chemistry最新文献

Despite the widespread success of the restrained electrostatic potential (RESP) method in molecular simulations, its high computational cost due to dense molecular electrostatic potential (MEP) sampling limits its application in large-scale systems. Here we present DF-RESP, which combines the density fitting MEP (DF-MEP) method with RESP charge derivation to dramatically accelerate calculations while maintaining accuracy. Compared to conventional RESP calculations, DF-RESP achieves excellent accuracy with a mean absolute error (MAE) in charges below 0.003 e for the S22 benchmark and electrostatic interaction energy deviations under 0.1 kcal/mol. For androgen receptor–ligand complexes, DF-RESP achieves an MAE of less than 0.06 kcal/mol. Notably, DF-RESP precisely captures conformational energy variations in Ser-Ala-Gly tripeptide dynamics through charge analysis and achieves a 14-fold speedup for the 1493-atom protein 1h59 while maintaining comparable accuracy. These results demonstrate that DF-RESP is a computationally efficient and reliable approach for RESP charge calculations in large-scale biomolecular simulations.

Calcium bismuth chloride (Ca₃BiCl₃), an accessible and nontoxic chemical, exhibits considerable promise as a photovoltaic absorber material. This research investigates the structural, optical, and electrical properties of Ca₃BiCl₃ utilizing the CASTEP module in the context of density functional theory (DFT). To enhance the photovoltaic efficacy of Ca₃BiCl₃-based solar cells (SCs), two hole transport layers (HTLs), Spiro-OMeTAD and P3HT, and two electron transport layers (ETLs), C₆₀ and WS₂, were investigated. The Solar Cell Capacitance Simulator (SCAPS-1D) was utilized to undertake a comprehensive numerical analysis of Ca₃BiCl₃ SCs, employing essential semiconductor equations such as Poisson's equation, the carrier continuity equations, and the drift-diffusion model. A comprehensive parameter analysis was performed, including factors such as layer thickness, doping density, temperature, carrier production and recombination rates, defect densities at the interfaces and the bulk material, quantum efficiency, and series vs. shunt resistance. After optimizing the ETL and HTL settings, a maximum power conversion efficiency (PCE) of 27.54% was attained using WS₂ as the ETL and P3HT as the HTL. This arrangement produced a short-circuit current density (J_SC) of 23.393 mA/cm², an open-circuit voltage (V_OC) of 1.313 V, and a fill factor (FF) of 89.64%. The results highlight the significant potential of Ca₃BiCl₃ as an effective absorber material, especially in conjunction with WS₂ and P3HT, for the progression of high-efficiency perovskite heterostructure SCs.

Frontier molecular orbitals play a crucial role in determining the magnetic behavior and exchange interactions in organic radicals. In this study, we investigate the underlying mechanism influencing the need for orbital planarity and the role of frontier orbital overlap in magnetic exchange interactions. To study this, we designed a series of 12 polyacene-coupled triarylmethyl diradicals, systematically increasing in length of polyacene. We have used nine different DFT functionals for the calculation of the magnetic exchange coupling constant (J). The calculation of magnetic exchange coupling reveals that the GGA functionals define a more accurate spin state, hence more correct magnetic behavior than the meta-GGA and hybrid functionals. We have studied the effect of orbital orientation and their energy gap to understand the high magnetic exchange coupling in the higher polyacene-coupled diradicals. Our calculations revealed that the planarity and overlap of the frontier molecular orbitals are one of the key factors in influencing the strength and behavior of the magnetic exchange interactions in diradicals. Specifically, the overlap between SOMOs and LUMO influences the strength of the magnetic exchange interaction.

The present study guides reliable and cost-effective computational approaches to metal-to-ligand charge transfer (MLCT) transitions in model [M(terpy)₂]²⁺ (M = Fe, Ru, Os) complexes relevant to electrochromic applications. We evaluated the performance of multireference perturbation theories (NEVPT2 and CASPT2), DLPNO-STEOM-CCSD, ADC(2), and 44 density functionals within TD-DFT for calculating vertical MLCT excitation energies in these systems. Multireference methods provide the most consistent agreement with experimental absorption maxima. The best theoretical estimates were obtained at the X2C NEVPT(14, 13)/x2c-QZVPPall level (2.368, 2.710, and 2.684 eV for M = Fe, Ru, and Os, respectively). DLPNO-STEOM-CCSD fails for [Fe(terpy)₂]²⁺, presumably due to its multireference character. Among DFT functionals, local meta-GGAs such as r²SCAN offer the best trade-off between accuracy and computational cost.

This study presents a comprehensive first-principles and device-performance investigation of alkali metal-based anti-perovskites Z₃BrO (Z = K, Rb, Cs, and Fr) for advanced optoelectronic and photovoltaic applications. Using density functional theory (DFT) with GGA-PBE and mGGA-rSCAN functionals, we analyzed the structural, electronic, optical, mechanical, phonon, population, and thermoelectric properties of these compounds. All Z₃BrO materials exhibit direct band gaps and strong optical absorption in the visible–UV spectrum. Mechanical and phonon analyses confirm their dynamic and elastic stability, with K₃BrO showing superior mechanical robustness and Fr₃BrO demonstrating the highest Debye temperature. SCAPS-1D simulations were conducted on heterostructures incorporating K₃BrO, Rb₃BrO, and Cs₃BrO as absorber layers. The results revealed PCEs of 23.26% for K₃BrO, 25.58% for Rb₃BrO, and 26.43% for Cs₃BrO, highlighting the tunability and performance potential of these materials. Fr₃BrO, while excluded from device simulation due to its near-metallic nature, exhibited promising optical and thermal features. These findings establish Z₃BrO anti-perovskites as promising, lead-free absorber materials for high-performance and sustainable solar energy technologies.

Quantum chemical calculations have been performed to investigate the structure, stability, and bonding in noble gas (Ng) bound Be₂B₅⁺ complexes. The present results show that Be₂B₅⁺, a charge-separated [Be]²⁺[B₅]³⁻[Be]²⁺ cluster, can employ both its cationic Be center and anionic B center to bind Ng atoms. It can bind a total of seven Ng atoms, resulting in the formation of a highly symmetric (Ng^Be)₂Be₂(Ng^B)₅B₅⁺ complex, having D_5h point group. The thermochemical analyses reveal that the Ng-Be bonds are stronger than the Ng-B bonds. (Ng^Be)₂Be₂B₅⁺ (Ng = Ar-Rn) complexes are stable against the dissociation of Ng atoms even at room temperature. But, (Ng^Be)₂Be₂B₅⁺ (Ng = He and Ne) and (Ng^Be)₂Be₂(Ng^B)₅B₅⁺ (Ng = Ar-Rn) complexes are stable only at very low temperatures. Therefore, they can be suitable candidates for low-temperature matrix isolation. A thorough bonding analysis, through charge and energy decomposition methods, discloses that despite the Ng-B interaction being weaker than the Ng-Be interaction, the former bond is more covalent than the latter one. In fact, in the Ng-B bonds, both the orbital and electrostatic interactions are larger in magnitude than the Ng-Be bonds; however, significantly larger Pauli repulsion in the former bonds makes them weaker than the latter bonds. In both Ng-Be and Ng-B bonds, the covalent interaction originates from a strong Ng(p_σ) → Be₂B₅⁺ σ donation, complemented by two weak Ng(p_π) → Be₂B₅⁺ π donations.

Significant amounts of effluents containing pharmaceuticals residues are released each year in the environment. These residues are responsible for the disruption of the metabolism of organisms. In this study, vermiculite, a low-cost and high specific area clay material, is a best and effective way to remove the micro-pollutants by adsorption. Thus, we investigate the adsorption of carbamazepine (CAR), aspirin (ASP), diazepam (DIA), diclofenac (DIC), paracetamol (PAR), and ibuprofen (IBU), the most common pharmaceutical pollutants encountered in wastewater, on the hydrated surface of vermiculite exchanged with magnesium using thermodynamic calculations and density functional theory (DFT). Our results indicate that DIC exhibits the highest affinity for the hydrated surface of vermiculite, followed by PAR, IBU, ASP, CAR, and DIA. Furthermore, it is possible to regenerate the adsorbent after use, just by heating the vermiculite to a temperature of 360 K. The adsorptions are all exothermic, with energies depending upon the structural configuration of the pollutant on the surface.