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151. Acetylene: Synergy between theory and experiment.

Author

Lundberg, James K., Field, Robert W., Sherrill, C. David, Seidl, Edward T., Xie, Yaoming, and Schaefer, Henry F.

Subjects
ACETYLENE, MOLECULAR electronics, SPECTRUM analysis, FORCE & energy
Abstract

Six anomalous vibronic feature states [∼2 cm-1 full-width at half-maximum (FWHM), each consisting of ∼20 partially resolved eigenstates] have been observed in stimulated emission pumping (SEP) spectra of C2D2. Of the two plausible assignments for these features, the one most consistent with spectroscopic observations would imply that the lowest energy cis-bent triplet state of acetylene has T0≤25 820 cm-1, which is inconsistent with previous ab initio predictions. New higher level ab initio quantum mechanical methods have been used to predict the energy difference between X 1Σg+ ground state and the cis-bent a 3B2 lowest triplet state of acetylene. In conjunction with a triple zeta plus double polarization plus f function (TZ2Pf) basis set, the coupled cluster including single, double, and linearized triple excitations CCSD(T) method yields T0=ΔE(a 3B2–X 1Σg+)=30 500 cm-1. The true value of T0 for the a 3B2 state is estimated to be ∼500 cm-1 higher. At the same level of theory the zero-point levels of the lowest triplet state of the trans-bent (a 3Bu) and vinylidene (a 3B2) isomers lie at still higher energies. This result conclusively rules out any triplet assignment for the anomalous feature states. The alternative assignment, as highly excited vibrational levels of the X 1Σg+ state, is surprising in view of the Franck–Condon selectivity, dynamical stability, and nonselective relaxation of this special class of ‘‘bright states’’ observed in the SEP spectra.Such an assignment would be implausible in the absence of the present ab initio calculations. Previous experimental observations [Lisy and Klemperer, J. Chem. Phys. 72, 3880 (1980) and Wendt, Hippler, and Hunziker, J. Chem. Phys. 70, 4044 (1979)] of acetylene triplet states are discussed and shown to be completely consistent with each other and with the present ab initio ordering of the cis and trans isomeric minima... [ABSTRACT FROM AUTHOR]

Published
1993
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152. Accurately Characterizing the π−π Interaction Energies of Indole−Benzene Complexes

Author

Geng, Yue, Takatani, Tait, Hohenstein, Edward G., and Sherrill, C. David

Abstract

Noncovalent interactions play a significant role in determining the structures of DNA, RNA, and proteins. Among the most prevalent are π−π interactions, which occur as favorable forces between the aromatic subunits of biochemical molecules. The aromatic side chains of amino acids tryptophan and phenylalanine are commonly modeled with indole and benzene, respectively. We have utilized the MP2 and SCS-MP2 methods with the aug-cc-pVDZ basis set to compute several T-shaped interaction energies and parallel displaced (PD) three-dimensional potential energy surfaces (PESs) at 3.4, 3.6, and 3.8 Å vertical separations. At selected minima, CCSD(T) results extrapolated to the complete-basis-set (CBS) limit were obtained. The trend of the T-shaped interactions has been rationalized by considering electrostatic potential maps and symmetry-adapted perturbation theory (SAPT) results. The global minimum has been verified to be the N−H/π T-shaped configuration with a CCSD(T)/CBS interaction energy of −5.62 kcal mol−1. For the PD PESs, the MP2 and SCS-MP2 methods predict different minimum configurations. The CCSD(T) method favors the SCS-MP2 PD configuration over the MP2 PD configuration by 0.18 kcal mol−1. Among the approximate methods considered here, the SCS-CCSD method extrapolated to the CBS limit incurs only around 2% error compared to CCSD(T)/CBS results and is the most reliable for the interaction energies of the indole−benzene complex. Overall, the extension of aromaticity and the highly positive hydrogen of the N−H bond, both exhibited by indole, enhance the strength of nonbonded interactions with benzene compared to those in the benzene dimer or in the pyridine-benzene complex.

Published
2024
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153. Directional ΔGNeural Network (DrΔG-Net): A Modular Neural Network Approach to Binding Free Energy Prediction

Author

Metcalf, Derek P., Glick, Zachary L., Bortolato, Andrea, Jiang, Andy, Cheney, Daniel L., and Sherrill, C. David

Abstract

The protein–ligand binding free energy is a central quantity in structure-based computational drug discovery efforts. Although popular alchemical methods provide sound statistical means of computing the binding free energy of a large breadth of systems, they are generally too costly to be applied at the same frequency as end point or ligand-based methods. By contrast, these data-driven approaches are typically fast enough to address thousands of systems but with reduced transferability to unseen systems. We introduce DrΔG-Net (or simply Dragnet), an equivariant graph neural network that can blend ligand-based and protein–ligand data-driven approaches. It is based on a 3D fingerprint representation of the ligand alone and in complex with the protein target. Dragnet is a global scoring function to predict the binding affinity of arbitrary protein–ligand complexes, but can be easily tuned via transfer learning to specific systems or end points, performing similarly to common 2D ligand-based approaches in these tasks. Dragnet is evaluated on a total of 28 validation proteins with a set of congeneric ligands derived from the Binding DB and one custom set extracted from the ChEMBL Database. In general, a handful of experimental binding affinities are sufficient to optimize the scoring function for a particular protein and ligand scaffold. When not available, predictions from physics-based methods such as absolute free energy perturbation can be used for the transfer learning tuning of Dragnet. Furthermore, we use our data to illustrate the present limitations of data-driven modeling of binding free energy predictions.

Published
2024
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158. Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Author

Shao, Yihan, Gan, Zhengting, Epifanovsky, Evgeny, Gilbert, Andrew T. B., Wormit, Michael, Kussmann, Joerg, Lange, Adrian W., Behn, Andrew, Deng, Jia, Feng, Xintian, Ghosh, Debashree, Stein, Tamar, Stück, David, Su, Yu-Chuan, Thom, Alex J.W., Tsuchimochi, Takashi, Vanovschi, Vitalii, Vogt, Leslie, Vydrov, Oleg, Wang, Tao, Watson, Mark A., Goldey, Matthew, Wenzel, Jan, White, Alec, Williams, Christopher F., Yang, Jun, Yeganeh, Sina, Yost, Shane R., You, Zhi-Qiang, Zhang, Igor Ying, Zhang, Xing, Zhao, Yan, Horn, Paul R., Brooks, Bernard R., Chan, Garnet K.L., Chipman, Daniel M., Cramer, Christopher J., Goddard, William A., Gordon, Mark S., Hehre, Warren, Klamt, Andreas, Schaefer, Henry F., Schmidt, Michael W., Jacobson, Leif D., Sherrill, C. David, Truhlar, Donald G., Warshel, Arieh, Xu, Xin, Aspuru-Guzik, Alán, Baer, Roi, Bell, Alexis T., Besley, Nicholas A., Chai, Jeng-Da, Dreuw, Andreas, Kaliman, Ilya, Dunietz, Barry D., Furlani, Thomas R., Gwaltney, Steven R., Hsu, Chao-Ping, Jung, Yousung, Kong, Jing, Lambrecht, Daniel S., Liang, WanZhen, Ochsenfeld, Christian, Rassolov, Vitaly A., Khaliullin, Rustam Z., Slipchenko, Lyudmila V., Subotnik, Joseph E., Van Voorhis, Troy, Herbert, John M., Krylov, Anna I., Gill, Peter M.W., Head-Gordon, Martin, Kuś, Tomasz, Landau, Arie, Liu, Jie, Proynov, Emil I., Rhee, Young Min, Richard, Ryan M., Rohrdanz, Mary A., Steele, Ryan P., Sundstrom, Eric J., Woodcock, H. Lee, Zimmerman, Paul M., Zuev, Dmitry, Albrecht, Ben, Alguire, Ethan, Austin, Brian, Beran, Gregory J. O., Bernard, Yves A., Berquist, Eric, Brandhorst, Kai, Bravaya, Ksenia B., Brown, Shawn T., Casanova, David, Chang, Chun-Min, Chen, Yunqing, Chien, Siu Hung, Closser, Kristina D., Crittenden, Deborah L., Diedenhofen, Michael, DiStasio, Robert A., Do, Hainam, Dutoi, Anthony D., Edgar, Richard G., Fatehi, Shervin, Fusti-Molnar, Laszlo, Ghysels, An, Golubeva-Zadorozhnaya, Anna, Gomes, Joseph, Hanson-Heine, Magnus W.D., Harbach, Philipp H.P., Hauser, Andreas W., Hohenstein, Edward G., Holden, Zachary C., Jagau, Thomas-C., Ji, Hyunjun, Kaduk, Benjamin, Khistyaev, Kirill, Kim, Jaehoon, Kim, Jihan, King, Rollin A., Klunzinger, Phil, Kosenkov, Dmytro, Kowalczyk, Tim, Krauter, Caroline M., Lao, Ka Un, Laurent, Adèle D., Lawler, Keith V., Levchenko, Sergey V., Lin, Ching Yeh, Liu, Fenglai, Livshits, Ester, Lochan, Rohini C., Luenser, Arne, Manohar, Prashant, Manzer, Samuel F., Mao, Shan-Ping, Mardirossian, Narbe, Marenich, Aleksandr V., Maurer, Simon A., Mayhall, Nicholas J., Neuscamman, Eric, Oana, C. Melania, Olivares-Amaya, Roberto, O’Neill, Darragh P., Parkhill, John A., Perrine, Trilisa M., Peverati, Roberto, Prociuk, Alexander, Rehn, Dirk R., Rosta, Edina, Russ, Nicholas J., Sharada, Shaama M., Sharma, Sandeep, Small, David W., Sodt, Alexander, Shao, Yihan, Gan, Zhengting, Epifanovsky, Evgeny, Gilbert, Andrew T. B., Wormit, Michael, Kussmann, Joerg, Lange, Adrian W., Behn, Andrew, Deng, Jia, Feng, Xintian, Ghosh, Debashree, Stein, Tamar, Stück, David, Su, Yu-Chuan, Thom, Alex J.W., Tsuchimochi, Takashi, Vanovschi, Vitalii, Vogt, Leslie, Vydrov, Oleg, Wang, Tao, Watson, Mark A., Goldey, Matthew, Wenzel, Jan, White, Alec, Williams, Christopher F., Yang, Jun, Yeganeh, Sina, Yost, Shane R., You, Zhi-Qiang, Zhang, Igor Ying, Zhang, Xing, Zhao, Yan, Horn, Paul R., Brooks, Bernard R., Chan, Garnet K.L., Chipman, Daniel M., Cramer, Christopher J., Goddard, William A., Gordon, Mark S., Hehre, Warren, Klamt, Andreas, Schaefer, Henry F., Schmidt, Michael W., Jacobson, Leif D., Sherrill, C. David, Truhlar, Donald G., Warshel, Arieh, Xu, Xin, Aspuru-Guzik, Alán, Baer, Roi, Bell, Alexis T., Besley, Nicholas A., Chai, Jeng-Da, Dreuw, Andreas, Kaliman, Ilya, Dunietz, Barry D., Furlani, Thomas R., Gwaltney, Steven R., Hsu, Chao-Ping, Jung, Yousung, Kong, Jing, Lambrecht, Daniel S., Liang, WanZhen, Ochsenfeld, Christian, Rassolov, Vitaly A., Khaliullin, Rustam Z., Slipchenko, Lyudmila V., Subotnik, Joseph E., Van Voorhis, Troy, Herbert, John M., Krylov, Anna I., Gill, Peter M.W., Head-Gordon, Martin, Kuś, Tomasz, Landau, Arie, Liu, Jie, Proynov, Emil I., Rhee, Young Min, Richard, Ryan M., Rohrdanz, Mary A., Steele, Ryan P., Sundstrom, Eric J., Woodcock, H. Lee, Zimmerman, Paul M., Zuev, Dmitry, Albrecht, Ben, Alguire, Ethan, Austin, Brian, Beran, Gregory J. O., Bernard, Yves A., Berquist, Eric, Brandhorst, Kai, Bravaya, Ksenia B., Brown, Shawn T., Casanova, David, Chang, Chun-Min, Chen, Yunqing, Chien, Siu Hung, Closser, Kristina D., Crittenden, Deborah L., Diedenhofen, Michael, DiStasio, Robert A., Do, Hainam, Dutoi, Anthony D., Edgar, Richard G., Fatehi, Shervin, Fusti-Molnar, Laszlo, Ghysels, An, Golubeva-Zadorozhnaya, Anna, Gomes, Joseph, Hanson-Heine, Magnus W.D., Harbach, Philipp H.P., Hauser, Andreas W., Hohenstein, Edward G., Holden, Zachary C., Jagau, Thomas-C., Ji, Hyunjun, Kaduk, Benjamin, Khistyaev, Kirill, Kim, Jaehoon, Kim, Jihan, King, Rollin A., Klunzinger, Phil, Kosenkov, Dmytro, Kowalczyk, Tim, Krauter, Caroline M., Lao, Ka Un, Laurent, Adèle D., Lawler, Keith V., Levchenko, Sergey V., Lin, Ching Yeh, Liu, Fenglai, Livshits, Ester, Lochan, Rohini C., Luenser, Arne, Manohar, Prashant, Manzer, Samuel F., Mao, Shan-Ping, Mardirossian, Narbe, Marenich, Aleksandr V., Maurer, Simon A., Mayhall, Nicholas J., Neuscamman, Eric, Oana, C. Melania, Olivares-Amaya, Roberto, O’Neill, Darragh P., Parkhill, John A., Perrine, Trilisa M., Peverati, Roberto, Prociuk, Alexander, Rehn, Dirk R., Rosta, Edina, Russ, Nicholas J., Sharada, Shaama M., Sharma, Sandeep, Small, David W., and Sodt, Alexander

Abstract

A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller–Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.

Published
2015

167. Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Author

Shao, Yihan, primary, Gan, Zhengting, additional, Epifanovsky, Evgeny, additional, Gilbert, Andrew T.B., additional, Wormit, Michael, additional, Kussmann, Joerg, additional, Lange, Adrian W., additional, Behn, Andrew, additional, Deng, Jia, additional, Feng, Xintian, additional, Ghosh, Debashree, additional, Goldey, Matthew, additional, Horn, Paul R., additional, Jacobson, Leif D., additional, Kaliman, Ilya, additional, Khaliullin, Rustam Z., additional, Kuś, Tomasz, additional, Landau, Arie, additional, Liu, Jie, additional, Proynov, Emil I., additional, Rhee, Young Min, additional, Richard, Ryan M., additional, Rohrdanz, Mary A., additional, Steele, Ryan P., additional, Sundstrom, Eric J., additional, Woodcock, H. Lee, additional, Zimmerman, Paul M., additional, Zuev, Dmitry, additional, Albrecht, Ben, additional, Alguire, Ethan, additional, Austin, Brian, additional, Beran, Gregory J. O., additional, Bernard, Yves A., additional, Berquist, Eric, additional, Brandhorst, Kai, additional, Bravaya, Ksenia B., additional, Brown, Shawn T., additional, Casanova, David, additional, Chang, Chun-Min, additional, Chen, Yunqing, additional, Chien, Siu Hung, additional, Closser, Kristina D., additional, Crittenden, Deborah L., additional, Diedenhofen, Michael, additional, DiStasio, Robert A., additional, Do, Hainam, additional, Dutoi, Anthony D., additional, Edgar, Richard G., additional, Fatehi, Shervin, additional, Fusti-Molnar, Laszlo, additional, Ghysels, An, additional, Golubeva-Zadorozhnaya, Anna, additional, Gomes, Joseph, additional, Hanson-Heine, Magnus W.D., additional, Harbach, Philipp H.P., additional, Hauser, Andreas W., additional, Hohenstein, Edward G., additional, Holden, Zachary C., additional, Jagau, Thomas-C., additional, Ji, Hyunjun, additional, Kaduk, Benjamin, additional, Khistyaev, Kirill, additional, Kim, Jaehoon, additional, Kim, Jihan, additional, King, Rollin A., additional, Klunzinger, Phil, additional, Kosenkov, Dmytro, additional, Kowalczyk, Tim, additional, Krauter, Caroline M., additional, Lao, Ka Un, additional, Laurent, Adèle D., additional, Lawler, Keith V., additional, Levchenko, Sergey V., additional, Lin, Ching Yeh, additional, Liu, Fenglai, additional, Livshits, Ester, additional, Lochan, Rohini C., additional, Luenser, Arne, additional, Manohar, Prashant, additional, Manzer, Samuel F., additional, Mao, Shan-Ping, additional, Mardirossian, Narbe, additional, Marenich, Aleksandr V., additional, Maurer, Simon A., additional, Mayhall, Nicholas J., additional, Neuscamman, Eric, additional, Oana, C. Melania, additional, Olivares-Amaya, Roberto, additional, O’Neill, Darragh P., additional, Parkhill, John A., additional, Perrine, Trilisa M., additional, Peverati, Roberto, additional, Prociuk, Alexander, additional, Rehn, Dirk R., additional, Rosta, Edina, additional, Russ, Nicholas J., additional, Sharada, Shaama M., additional, Sharma, Sandeep, additional, Small, David W., additional, Sodt, Alexander, additional, Stein, Tamar, additional, Stück, David, additional, Su, Yu-Chuan, additional, Thom, Alex J.W., additional, Tsuchimochi, Takashi, additional, Vanovschi, Vitalii, additional, Vogt, Leslie, additional, Vydrov, Oleg, additional, Wang, Tao, additional, Watson, Mark A., additional, Wenzel, Jan, additional, White, Alec, additional, Williams, Christopher F., additional, Yang, Jun, additional, Yeganeh, Sina, additional, Yost, Shane R., additional, You, Zhi-Qiang, additional, Zhang, Igor Ying, additional, Zhang, Xing, additional, Zhao, Yan, additional, Brooks, Bernard R., additional, Chan, Garnet K.L., additional, Chipman, Daniel M., additional, Cramer, Christopher J., additional, Goddard, William A., additional, Gordon, Mark S., additional, Hehre, Warren J., additional, Klamt, Andreas, additional, Schaefer, Henry F., additional, Schmidt, Michael W., additional, Sherrill, C. David, additional, Truhlar, Donald G., additional, Warshel, Arieh, additional, Xu, Xin, additional, Aspuru-Guzik, Alán, additional, Baer, Roi, additional, Bell, Alexis T., additional, Besley, Nicholas A., additional, Chai, Jeng-Da, additional, Dreuw, Andreas, additional, Dunietz, Barry D., additional, Furlani, Thomas R., additional, Gwaltney, Steven R., additional, Hsu, Chao-Ping, additional, Jung, Yousung, additional, Kong, Jing, additional, Lambrecht, Daniel S., additional, Liang, WanZhen, additional, Ochsenfeld, Christian, additional, Rassolov, Vitaly A., additional, Slipchenko, Lyudmila V., additional, Subotnik, Joseph E., additional, Van Voorhis, Troy, additional, Herbert, John M., additional, Krylov, Anna I., additional, Gill, Peter M.W., additional, and Head-Gordon, Martin, additional

Published
2014
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179. Analysis of transition state stabilization by non-covalent interactions in the Houk–List model of organocatalyzed intermolecular Aldol additions using functional-group symmetry-adapted perturbation theory.

Author

Bakr, Brandon W. and Sherrill, C. David

Abstract

Rational design of catalysts would be aided by a better understanding of how non-covalent interactions stabilize transition states. Here, we apply the newly-developed Functional-Group Symmetry-Adapted Perturbation Theory (F-SAPT) to quantify non-covalent interactions in transition states of the proline-catalyzed intermolecular aldol reaction between benzaldehyde and cyclohexanone, according to the Houk–List mechanism [Bahmanyar et al., J. Am. Chem. Soc., 2003, 125, 2475]. A recent re-examination of this organocatalytic reaction by Rzepa and co-workers [Armstrong et al., Chem. Sci., 2014, 5, 2057] used electron density analysis to identify three key non-covalent interactions thought to influence stereoselectivity: (1) a favorable electrostatic interaction (originally identified by Houk and List) between the NCHδ+ group of the enamine intermediate and the δ−O=C of benzaldehyde; (2) a C–H/π interaction between the cyclohexene group of the enamine intermediate and the benzaldehyde phenyl ring; (3) a stabilizing contact between an ortho-hydrogen of the phenyl and an oxygen of the carboxylic acid group of the enamine. These three interactions have been directly computed using F-SAPT, which confirms the stabilizing interaction between an ortho-hydrogen and the carboxylic acid in the (S,S) and (R,S) transition state stereoisomers. F-SAPT analysis also finds stabilizing dispersion and electrostatic interactions due to a C–H/π interaction between the cyclohexene and phenyl groups in the (S,S) and (R,R) transition states. However, unfavorable exchange-repulsion cancels the attractive terms that favor these stereoisomers. Surprisingly, the interaction thought to be most important for stereoselectivity, the NCHδ+…δ−O=C interaction, is actually found to be repulsive due to the negative charge on the nitrogen. Hence, our results indicate that geometric analysis and/or density-based analysis does not necessarily produce a reliable picture of non-covalent stabilization. As confirmed by high-level coupled-cluster computations, intermolecular interaction energies are strongest for the (R,R) transition states, which are not the experimentally favored products. This suggests that at least for this reaction, stereoselectivity is also strongly dependent on the energy required to distort the reacting molecules into the transition state geometry. [ABSTRACT FROM AUTHOR]

Published
2016
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188. Psi41.1: An Open-Source Electronic Structure Program Emphasizing Automation, Advanced Libraries, and Interoperability

Author

Parrish, Robert M., Burns, Lori A., Smith, Daniel G. A., Simmonett, Andrew C., DePrince, A. Eugene, Hohenstein, Edward G., Bozkaya, Uğur, Sokolov, Alexander Yu., Di Remigio, Roberto, Richard, Ryan M., Gonthier, Jérôme F., James, Andrew M., McAlexander, Harley R., Kumar, Ashutosh, Saitow, Masaaki, Wang, Xiao, Pritchard, Benjamin P., Verma, Prakash, Schaefer, Henry F., Patkowski, Konrad, King, Rollin A., Valeev, Edward F., Evangelista, Francesco A., Turney, Justin M., Crawford, T. Daniel, and Sherrill, C. David

Abstract

Psi4is an ab initio electronic structure program providing methods such as Hartree–Fock, density functional theory, configuration interaction, and coupled-cluster theory. The 1.1 release represents a major update meant to automate complex tasks, such as geometry optimization using complete-basis-set extrapolation or focal-point methods. Conversion of the top-level code to a Python module means that Psi4can now be used in complex workflows alongside other Python tools. Several new features have been added with the aid of libraries providing easy access to techniques such as density fitting, Cholesky decomposition, and Laplace denominators. The build system has been completely rewritten to simplify interoperability with independent, reusable software components for quantum chemistry. Finally, a wide range of new theoretical methods and analyses have been added to the code base, including functional-group and open-shell symmetry adapted perturbation theory, density-fitted coupled cluster with frozen natural orbitals, orbital-optimized perturbation and coupled-cluster methods (e.g., OO-MP2 and OO-LCCD), density-fitted multiconfigurational self-consistent field, density cumulant functional theory, algebraic-diagrammatic construction excited states, improvements to the geometry optimizer, and the “X2C” approach to relativistic corrections, among many other improvements.

Published
2017
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189. Comparison of Explicitly Correlated Methods for Computing High-Accuracy Benchmark Energies for Noncovalent Interactions

Author

Sirianni, Dominic A., Burns, Lori A., and Sherrill, C. David

Abstract

The reliability of explicitly correlated methods for providing benchmark-quality noncovalent interaction energies was tested at various levels of theory and compared to estimates of the complete basis set (CBS) limit. For all systems of the A24 test set, computations were performed using both aug-cc-pVXZ (aXZ; X = D, T, Q, 5) basis sets and specialized cc-pVXZ-F12 (XZ-F12; X = D, T, Q, 5) basis sets paired with explicitly correlated coupled cluster singles and doubles [CCSD-F12n (n = a, b, c)] with triple excitations treated by the canonical perturbative method and scaled to compensate for their lack of explicit correlation [(T**)]. Results show that aXZ basis sets produce smaller errors versus the CBS limit than XZ-F12 basis sets. The F12b ansatz results in the lowest average errors for aTZ and larger basis sets, while F12a is best for double-ζ basis sets. When using aXZ basis sets (X ≥ 3), convergence is achieved from above for F12b and F12c ansatzë and from below for F12a. The CCSD(T**)-F12b/aXZ approach converges quicker with respect to basis than any other combination, although the performance of CCSD(T**)-F12c/aXZ is very similar. Both CCSD(T**)-F12b/aTZ and focal point schemes employing density-fitted, frozen natural orbital [DF-FNO] CCSD(T)/aTZ exhibit similar accuracy and computational cost, and both are much more computationally efficient than large-basis conventional CCSD(T) computations of similar accuracy.

Published
2017
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192. Psi4: an open-source ab initio electronic structure program

Author

Turney, Justin M., primary, Simmonett, Andrew C., additional, Parrish, Robert M., additional, Hohenstein, Edward G., additional, Evangelista, Francesco A., additional, Fermann, Justin T., additional, Mintz, Benjamin J., additional, Burns, Lori A., additional, Wilke, Jeremiah J., additional, Abrams, Micah L., additional, Russ, Nicholas J., additional, Leininger, Matthew L., additional, Janssen, Curtis L., additional, Seidl, Edward T., additional, Allen, Wesley D., additional, Schaefer, Henry F., additional, King, Rollin A., additional, Valeev, Edward F., additional, Sherrill, C. David, additional, and Crawford, T. Daniel, additional

Published
2011
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