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doi: 10.1002/jcc.26892pmid: 35709311
In the present study, we have investigated the performance of RIJCOSX DLPNO‐CCSD(T)‐F12 methods for a wide range of systems. Calculations with a high‐accuracy option [“DefGrid3 RIJCOSX DLPNO‐CCSD(T1)‐F12”] extrapolated to the complete‐basis‐set limit using the maug‐cc‐pV[D+d,T+d]Z basis sets provides fairly good agreements with the canonical CCSD(T)/CBS reference for a diverse set of thermochemical and kinetic properties [with mean absolute deviations (MADs) of ~1–2 kJ mol−1 except for atomization energies]. On the other hand, the low‐cost “RIJCOSX DLPNO‐CCSD(T)‐F12D” option leads to substantial deviations for certain properties, notably atomization energies (MADs of up to tens of kJ mol−1). With the high‐accuracy CBS approach, we have formulated the L‐W1X method, which further includes a low‐cost core–valence plus scalar‐relativistic term. It shows generally good accuracy. For improved accuracies in specific cases, we advise replacing maug‐cc‐pV(n+d)Z with jun‐cc‐pV(n+d)Z for the calculation of electron affinities, and using well‐constructed isodesmic‐type reactions to obtain atomization energies. For medium‐sized systems, DefGrid3 RIJCOSX DLPNO‐CCSD(T1)‐F12 calculations are several times faster than the corresponding canonical computation; the use of the local approximations (RIJCOSX and DLPNO) leads to a better scaling than that for the canonical calculation (from ~6–7 down to ~2–4 for our test systems). Thus, the DefGrid3 RIJCOSX DLPNO‐CCSD(T1)‐F12 method, and the L‐W1X protocol that based on it, represent a useful means for obtaining accurate thermochemical quantities for larger systems.
Rayón, Víctor M.; Cabria, Iván
doi: 10.1002/jcc.26945pmid: 35668546
Experimental isotherms of N2 and CO2 on carbon‐based porous materials and models of the physisorption of gases on surfaces are used to obtain the pore size distribution (PSD). An accurate modelization of the physisorption of N2 and CO2 on the surface of carbon‐based porous materials is important to obtain accurate N2 and CO2 storage capacities and reliable PSDs. Physisorption depends on the dispersion interactions. High precision ab initio methods, such as CCSD(T), consider accurately the dispersion interactions, but they are computationally expensive. Double hybrid, hybrid and DFT‐based methods are much less expensive. In the case of graphene, there are experimental data of the adsorption of N2 and CO2 on graphite that can be used to build the Steele interaction potential of these gases on graphene. The goal is to find out hybrid and/or DFT methods that are as accurate as the CCSD(T) on benzene and as accurate as the experimental results on graphene. Calculations of the interaction energy curves of N2 and CO2 on benzene and graphene have been carried out using the CCSD(T) method and several double hybrid, hybrid, and DFT methods that consider the dispersion interactions. The energy curves on benzene have been compared to the CCSD(T) and the energy curves on graphene have been compared with the Steele energy curves. The comparisons indicate that double hybrids with dispersion corrections and ωB97 based DFT methods are accurate enough for benzene. For graphene, only the PBE‐XDM functional has a good agreement with the Steele energy curves.
Salta, Zoi; Vega‐Teijido, Mauricio; Katz, Aline; Tasinato, Nicola; Barone, Vincenzo; Ventura, Oscar N.
doi: 10.1002/jcc.26946pmid: 35662073
Methods rooted in the density functional theory and in the coupled cluster ansatz were employed to investigate the cycloaddition reactions to ethylene and acetylene of 1,3‐dipolar species including ozone and the derivatives issued from replacement of the central oxygen atom by the valence‐isoelectronic sulfur atom, and/or of one or both terminal oxygen atoms by the isoelectronic CH2 group. This gives rise to five different 1,3‐dipolar compounds, namely ozone itself (O3), sulfur dioxide (SO2), the simplest Criegee intermediate (CH2OO), sulfine (CH2SO), and thioformaldehyde S‐methylide (CH2SCH2, TSM). The experimental and accurate theoretical data available for some of those molecules were employed to assess the accuracy of two last‐generation composite methods employing conventional or explicitly correlated post‐Hartree‐Fock contributions (jun‐Cheap and SVECV‐f12, respectively), which were then applied to investigate the reactivity of TSM. The energy barriers provided by both composite methods are very close (the average values for the two composite methods are 7.1 and 8.3 kcal mol−1 for the addition to ethylene and acetylene, respectively) and comparable to those ruling the corresponding additions of ozone (4.0 and 7.7 kcal mol−1, respectively). These and other evidences strongly suggest that, at least in the case of cycloadditions, the reactivity of TSM is similar to that of O3 and very different from that of SO2.
Andreadi, Nikolai; Zankov, Dmitry; Karpov, Kirill; Mitrofanov, Artem
doi: 10.1002/jcc.26947pmid: 35678223
Finding global and local minima on the potential energy surface is a key task for most studies in computational chemistry. Having a set of possible conformations for chemical structures and their corresponding energies, one can judge their chemical activity, understand the mechanisms of reactions, describe the formation of metal‐ligand and ligand‐protein complexes, and so forth. Despite the fact that the interest in various minima search algorithms in computational chemistry arose a while ago (during the formation of this science), new methods are still emerging. These methods allow to perform conformational analysis and geometry optimization faster, more accurately, or for more specific tasks. This article presents the application of a novel global geometry optimization approach based on the Tree Parzen Estimator method. For benchmarking, a database of small organic molecule geometries in the global minimum conformation was created, as well as a software package to perform the tests.
Solov'yov, Ilia A.; Sushko, Gennady; Friis, Ida; Solov'yov, Andrey V.
doi: 10.1002/jcc.26948pmid: 35708151
Stochastic dynamics describes processes in complex systems having the probabilistic nature. They can involve very different dynamical systems and occur on very different temporal and spatial scale. This paper discusses the concept of stochastic dynamics and its implementation in the popular program MBN Explorer. Stochastic dynamics in MBN Explorer relies on the Monte Carlo approach and permits simulations of physical, chemical, and biological processes. The paper presents the basic theoretical concepts underlying stochastic dynamics implementation and provides several examples highlighting its applicability to different systems, such as diffusing proteins seeking an anchor point on a cell membrane, deposition of nanoparticles on a surface leading to structures with fractal morphologies, and oscillations of compounds in an autocatalytic reaction. The chosen examples illustrate the diversity of applications that can be modeled by means of stochastic dynamics with MBN Explorer.
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