The hybrid quantum mechanics/molecular mechanics (QM/MM) method IMOMM is applied to the calculation of the reaction of thiophene with Cp*RhPMe3 , which is a good experimental model for homogeneous catalytic hydrodesulfurization (HDS). The validity of the results is checked by comparison with previously reported full QM calculations on the same system. The geometries obtained with IMOMM are in g...

The calculation of binding affinities for flexible ligands has hitherto required the availability of reliable molecular mechanics parameters for the ligands, a restriction that can in principle be lifted by using a mixed quantum mechanics/molecular mechanics (QM/MM) representation in which the ligand is treated quantum mechanically. The feasibility of this approach is evaluated here, combining ...

The promiscuous activity of human carbonic anhydrase (hCAII) against a non-physiological cyanic acid substrate has been investigated by using a combined QM and QM/MM level of theory. Results show that the hCAII is able to hydrate the cyanic acid by a reaction mechanism similar to that of the CO2 native substrate. The energy barrier for the nucleophilic attack is found to be 15.6 and 4.3 kcal mo...

Quantum mechanics (QM) uses some unique notations to present its mathematical formalism. Due to historical reasons along the development path of QM, different scientists also used different representations in QM and its application. Even today, different notations and representations are still mixed in modern QM research and applications. These caused lots of confusions for beginners. Apparentl...

The explicit polarization (X-Pol) potential is an electronic-structure-based polarization force field, designed for molecular dynamics simulations and modeling of biopolymers. In this approach, molecular polarization and charge transfer effects are explicitly treated by a combined quantum mechanical and molecular mechanical (QM/MM) scheme, and the wave function of the entire system is variation...

Nanotwinned structures in superhard ceramics rhombohedral boron suboxide (R-B6O) have been examined using a combination of transmission electron microscopy (TEM) and quantum mechanics (QM). QM predicts negative relative energies to R-B6O for various twinned R-B6O (denoted as τ-B6O, 2τ-B6O, and 4τ-B6O), consistent with the recently predicted B6O structure with Cmcm space group (τ-B6O) which has ...

Abstract As online learning becomes increasingly popular in higher education, the quality of courses that utilize this modality is becoming a focus inquiry. Quality Matters (QM) leading assurance organization reviews and hybrid (partially online, partially in-person) for standards pedagogy instructional design certifies sufficiently meet these standards. In study, we examine student perceptions...

Quantum mechanics lies at the heart of chemistry. It is impossible to understand the structure of the Periodic Table, chemical bonding patterns, free energies of chemical reactions, reaction rates and branching ratios, and other chemical phenomena without a quantum-mechanical (QM) description. In particular, the dynamics of molecular systems often involve QM effects such as zero-point energy, t...

A molecular-orbital derived polarizable potential function is developed to model liquid and supercritical fluid hydrogen fluoride. The model is based on a novel application of a combined quantum-mechanical and molecular-mechanical ~QM/MM! approach, which treats molecular polarization by a semiempirical method. Two geometrical models are examined, differing in the intramolecular bond length for ...