Psi4 is a free and open-source ab initio electronic structure program providing Hartree-Fock, density functional theory, many-body perturbation theory, configuration interaction, density cumulant theory, symmetry-adapted perturbation theory, and coupled-cluster theory. Most of the methods are quite efficient thanks to density fitting and multi-core parallelism. The program is a hybrid of C++ and Python, and calculations may be run with very simple text files or using the Python API, facilitating post-processing and complex workflows; method developers also have access to most of Psi4's core functionality via Python. Job specification may be passed using The Molecular Sciences Software Institute (MolSSI) QCSchema data format, facilitating interoperability. A rewrite of our top-level computation driver, and concomitant adoption of the MolSSI QCArchive Infrastructure project, make the latest version of Psi4 well suited to distributed computation of large numbers of independent tasks. The project has fostered the development of independent software components that may be reused in other quantum chemistry programs. File list (2) download file view on ChemRxiv psi4.pdf (4.37 MiB) download file view on ChemRxiv supplementary_material.pdf (297.86 KiB)

The “Seven Pillars” of oxidation catalysis proposed by Robert K. Grasselli represent an early example of phenomenological descriptors in the field of heterogeneous catalysis. Major advances in the theoretical description of catalytic reactions have been achieved in recent years and new catalysts are predicted today by using computational methods. To tackle the immense complexity of high-performance systems in reactions where selectivity is a major issue, analysis of scientific data by artificial intelligence and data science provides new opportunities for achieving improved understanding. Modern data analytics require data of highest quality and sufficient diversity. Existing data, however, frequently do not comply with these constraints. Therefore, new concepts of data generation and management are needed. Herein we present a basic approach in defining best practice procedures of measuring consistent data sets in heterogeneous catalysis using “handbooks”. Selective oxidation of short-chain alkanes over mixed metal oxide catalysts was selected as an example.

By combining rotational spectroscopyinsupersonic expansion with the capability of state-of-the-art quantumchemical computations in accurately determining structural and energetic properties,the genuine nature of as ulfur-sulfur chalcogen bond between dimethyl sulfide and sulfur dioxide has been unveiled in agas-jet environment free from collision, solvent and matrix perturbations.ASAPT analysis pointed out that electrostatic S···S interactions play the dominant role in determining the stability of the complex, largely overcoming dispersion and CÀH···O hydrogen-bond contributions.Indeed, in agreement with the analysis of the quadrupole-coupling constants and of the methyl internal rotation barrier,the NBO and NOCV/CD approaches show am arked charge transfer between the sulfur atoms.B ased on the assignment of the rotational spectra for 7i sotopologues,a na ccurate semiexperimental equilibrium structure for the heavy-atom backbone of the molecular complex has been determined, whichis characterized by aS ···S distance (2.947(3) )w ell belowt he sum of van der Waals radii.

Boron nitride and related boron-containing materials have recently been suggested as very promising catalysts in the oxidative dehydrogenation of propane. The high selectivity towards propylene at comparably high conversion significantly exceeds the performance of established vanadium-based catalysts. In the current work we show that the high selectivity towards propylene and ethylene is fully consistent with a gas-phase conversion mechanism and that it can be modelled reasonably well by the recent detailed microkinetic reaction mechanism of Hashemi and coworkers. Our analysis, using six heterogeneous catalytic reaction pathways, each representing a hypothetical limit case, shows that the boron nitride catalyst is responsible for initiating the gas-phase chemistry. We also show that the experimental C 2 :C 1 product ratios with an undiluted catalytic bed can be reproduced by incorporating CC bond scission into the catalytic surface chemistry. The trends in the selectivities of minor species upon dilution of the catalytic bed and upon varying the C 3 H 8 /O 2 inlet ratio, as observed by Venegas and Hermans, are here explained as gas-phase phenomena. Hence, the oxidative dehydrogenation of propane over boron nitride catalysts is an example of a coupled gas-and catalytic-chemistry system. The current work also highlights the importance of modelling of the complete heated zone, including the rear heat shields and reactor padding if present.

<div> <div> <div> <p>Psi4 is a free and open-source ab initio electronic structure program providing Hartree–Fock, density functional theory, many-body perturbation theory, configuration interaction, density cumulant theory, symmetry-adapted perturbation theory, and coupled-cluster theory. Most of the methods are quite efficient thanks to density fitting and multi-core parallelism. The program is a hybrid of C++ and Python, and calculations may be run with very simple text files or using the Python API, facilitating post-processing and complex workflows; method developers also have access to most of Psi4’s core functionality via Python. Job specification may be passed using The Molecular Sciences Software Institute (MolSSI) QCSchema data format, facilitating interoperability. A rewrite of our top-level computation driver, and concomitant adoption of the MolSSI QCArchive Infrastructure project, make the latest version of Psi4 well suited to distributed computation of large numbers of independent tasks. The project has fostered the development of independent software components that may be reused in other quantum chemistry programs. </p> </div> </div> </div>