Browsing by Author "Truhlar, Donald G"

Now showing 1 - 6 of 6
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    Adiabatic and Diabatic Energy Data for the Ground and First Excited Singlet States of CH₃NH₂
    (2020-05-18) Parker, Kelsey A; Truhlar, Donald G; truhlar@umn.edu; Truhlar, Donald G; Truhlar Group, Department of Chemistry, UMN-TC
    This data set includes adiabatic energies from XMS-CASPT2/6-31++G(d,p) calculations and diabatic energies and couplings calculated using the dipole-quadrupole diabatization method for the ground and first excited singlet states of methylamine (CH₃NH₂) at 1825 geometry points. This data was used to construct an analytical diabatic potential energy matrix.
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    Electronic structure data for ³A´ and ³A´´ N₂O
    (2020-10-28) Lin, Wei; Varga, Zoltan; Song, Guoliang; Paukku, Yuliya; Truhlar, Donald G; truhlar@umn.edu; Truhlar, Donald G; University of Minnesota Department of Chemistry
    This dataset constitutes the electronic structure data that was fitted to obtain global reactive potential energy surfaces (PESs) for Born-Oppenheimer collisions of oxygen atoms with nitrogen molecules. In particular it contains data for the lowest-energy ³Α´ and ³A´´ PESs for the high-energy reaction N₂(X ¹Σ) + O(³P) → NO(X ²Π) + N(⁴S); these potential energy surfaces can serve to generate forces for dynamics calculations. The data was obtained by multireference configuration interaction (MRCI) calculations that were improved by a dynamically scaled external correlation (DSEC) term. The MRCI calculations are based on wave functions obtained from state-averaged complete active space self-consistent-field calculations for 2280 geometries for the three lowest ³A´´ states and for 2298 geometries for the three lowest ³A´ states. The lowest-energy ³A´ and ³A´´ state at each of these geometries was then improved by applying the DSEC method to all MRCI points.
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    Electronic structure data of singlet N₄
    (2020-04-24) Varga, Zoltan; Paukku, Yuliya; Truhlar, Donald G; truhlar@umn.edu; Truhlar, Donald G; Truhlar Group, Department of Chemistry. UMN
    Calculated electronic structure energies by CASPT2/maug-cc-pVTZ and CCSD(T)/maug-cc-pVTZ for 21406 geometry points of the singlet N₄ system. These points can be used to fit the global potential energy surface of the ground state of singlet N₄.
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    Minnesota Solvation Database (MNSOL) version 2012
    (2020-05-12) Marenich, Aleksandr V; Kelly, Casey P; Thompson, Jason D; Hawkins, Gregory D; Chambers, Candee C; Giesen, David J; Winget, Paul; Cramer, Christopher J; Truhlar, Donald G; truhlar@umn.edu; Truhlar, Donald G; Truhlar Research Group
    The Minnesota Solvation Database consists of a collection of 3037 experimental free energies of solvation or transfer free energies for 790 unique solutes in 92 solvents (including water) and gas-phase M06-2X/MG3S optimized molecular geometries in Cartesian coordinates for the corresponding solutes. All of the 790 solutes in this database (541 neutrals and 249 singly-charged ions) contain at most the following elements: H, C, N, O, F, Si, P, S, Cl, Br, and I.
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    Pilgrim 2020.1
    (2020-03-19) Ferro-Costas, David; Truhlar, Donald G; Fernandez-Ramos, Antonio; truhlar@umn.edu; Truhlar, Donald G; University of Minnesota Theoretical and Computational Chemistry Group
    Pilgrim is a program written in Python and designed to use direct dynamics in the calculation of thermal rate constants of chemical reactions by the variational transition state theory (VTST), based on electronic structure calculations for the potential energy surface. Pilgrim can also simulate reaction mechanisms using kinetic Monte Carlo (KMC). For reaction processes with many elementary steps, the rate constant of each of these steps can be calculated by means of conventional transition state theory (TST) or of the VTST. In the current version, Pilgrim can evaluate these thermal rates using the canonical version of reaction-path VTST, which requires the calculation of the minimum energy path (MEP) associated with each elementary step or transition structure. Multi-dimensional quantum effects can be incorporated through the small-curvature tunneling (SCT) approximation. These methodologies are available both for reactions involving a single structure of the reactants and the transition state and also for reactions involving flexible molecules with multiple conformations of the reactant and/or of the transition state. For systems with many conformers, the program can evaluate each of the elementary reactions by multi-path canonical VTST or multi-structural VTST. Moreover, the reactant can be unimolecular or bimolecular. Torsional anharmonicity can be incorporated through the MSTor and Q2DTor programs. Dual-level calculations are also available: automatic high-level single point energies can be used to correct the energy of reactants, transition states, products, and MEP points using the interpolated single-point energies (ISPE) algorithm. When the rate constants of all the chemical processes of interest are known, by means of their calculation using Pilgrim or alternatively through analytical fits to the rate constants as functions of temperature, it is possible to simulate the whole process using KMC. This algorithm allows performing a kinetic simulation to monitor the evolution of each chemical species with time and obtain the product yields.
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    PIPFit 2022
    (2022-02-14) Yang, Ke R; Varga, Zoltan; Parker, Kelsey A; Shu, Yinan; Truhlar, Donald G; truhlar@umn.edu; Truhlar, Donald G; Truhlar Research Group, Department of Chemistry, University of Minnesota
    The PIPFit 2022 program can be used to develop analytic representations of potential energy surfaces for three-body and four-body systems. A weighted least-squares fit is performed with permutationally invariant polynomials (PIPs) whose variables are Morse-like bond functions, Gaussians, mixed exponential–Gaussians (MEGs), or hyperbolic secant variables. Three kinds of fit can be performed with the program: