Ab initio Free Energy Calculations with Chemical Accuracy for Molecule-Surface Interactions
Final Report Abstract
The main goal of the project - development and application of methodology for the quantum mechanical ab initio prediction of free energies for large periodic systems with chemical accuracy (4.2 kJ/mol) has been reached, see Accounts of Chemical Research, Vol. 52, 2019, p. 3502- 3510. (1) With the MonaLisa code we have implemented a hybrid high level – low level approach that combines accurate wave-function methods for the reaction site (MP2) with less accurate, but computationally more efficient density functional theory with account of dispersion (DFT-D) for the full periodic system. This approach is used for single-point calculations or structure optimizations, whereas single-point Coupled Cluster corrections are added if needed to reach chemical accuracy. The method is named hybrid MP2:DFT-D + DCC. (2) For efficient local sampling of the potential energy surface, anharmonic vibrational frequencies are calculated for each degree of freedom separately by solving one-dimensional Schrödinger equations. The corresponding potentials are sampled in curvilinear coordinates. We have demonstrated that chemically accuracy Gibbs free energies are obtained for adsorption of small alkanes in acidic zeolites, of CO on the MgO(001) surface, and of CO and N2 in metalorganic frameworks (MOFs). Moreover, we obtained chemically accurate rate constants for the methylation of alkenes at acidic sites of zeolites. We have further applied this methodology to adsorption of methanol and ethanol in zeolite-H-MFI and employed it for the calculation of adsorption isotherms relevant for gas storage (H2, CH4) and gas separation (e.g., CH4/CO2) by MOFs. We have built a data base of nine molecule – surface interactions for which agreement has been achieved with experimental adsorption enthalpies and used it to assess the performance of some popular dispersion approaches with DFT-D. We have used our hybrid MP2:DFT-D + DCC method for energies together with harmonic partition functions to solve problems in catalysis by acidic zeolites: proton exchange barriers for alkanes, adsorption and cracking of propane, and adsorption and dimerization of alkenes. We have further developed the methodology in several directions: (i) Limitation of the anharmonicity calculations to the subspace of the six rigid-body coordinates which describe the (hindered) rotations and translations of the adsorbed species relative to the surface. (ii) Calculation of vibrational partition functions by integration of the vibrational density of states (VDOS) generated by short MD runs of the order of 10 ps. We have shown that direct integration leads to large errors resulting from contributions of overtones and combination bands, and that projection of the VDOS on normal modes is needed to avoid these errors. (iii) To include anharmonicity beyond the local Taylor expansion of the potential energy surface (PES), we have implemented a Grand Canonical Monte Carlo (GCMC) method on a lattice of adsorption site. The Hamiltonian uses Gibbs free energies for the individual adsorption sites which have been obtained with our anharmonic hybrid MP2:DFT-D + DCC method and takes the lateral interactions between adsorbed molecules explicitly into account. (iv) For 19 cases of alkane adsorption in zeolites with different pore sizes and Si/Al ratios, we have performed MD simulations in configuration space on a PES which is of hybrid MP2:DFT-D quality. The mean absolute deviation of the predicted heat of adsorption from experiment is as small as 1.9 kJ/mol. The key approximations are (a) sampling the configuration space at the DFT-D level, and (b) parametrizing the difference between hybrid MP2:DFT-D and DFT-D energies.
Publications
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Accurate Adsorption Thermodynamics of Small Alkanes in Zeolites. Ab initio Theory and Experiment for H- Chabazite, J. Phys. Chem. C 119 (2015) 6128-6137
G. Piccini, M. Alessio, J. Sauer, Y. Zhi, Y. Liu, R. Kolvenbach, A. Jentys, J. A. Lercher
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Ab initio calculation of rate constants for molecule - surface reactions with chemical accuracy, Angew. Chem. Int. Ed, 55 (2016) 5255-5257
G. Piccini, M. Alessio, J. Sauer
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Ab initio prediction of adsorption isotherms for small molecules in metal-organic frameworks, J. Am. Chem. Soc. 138 (2016) 14047-14056
A. Kundu, G. Piccini, K. Sillar, J. Sauer
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Ab Initio Adsorption Isotherms for Molecules with Lateral Interactions: CO2 in Metal-Organic Framework, J. Phys. Chem. C 121 (2017) 12789- 12799
K. Sillar, A. Kundu, J. Sauer
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Ab initio prediction of adsorption isotherms for gas mixtures by grand canonical Monte Carlo on a lattice of sites, J. Phys. Chem. Lett. 8 (2017) 2713-2718
A. Kundu, K. Sillar, J. Sauer
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Ab Initio Prediction of Proton Exchange Barriers for Alkanes at Brønsted Sites of Zeolite H-MFI, J. Am. Chem. Soc. 140 (2018) 18151 – 18161
M. Rybicki, J. Sauer
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Chemically Accurate Adsorption Energies for Methane and Ethane Monolayers on the MgO(001) Surface, Phys. Chem. Chem. Phys. 20 (2018) 9760-9769
M. Alessio, F. Bischoff, J. Sauer
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Ab Initio Calculations for Molecule-Surface Interactions with Chemical Accuracy, Acc. Chem. Res., 52 (2019) 3502-3510
J. Sauer
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Chemically Accurate Adsorption Energies: CO and H2O on the MgO(001) Surface, J. Chem. Theory Comput. 15 (2019) 1329 – 1344
M. Alessio, D. Usvyat, J. Sauer
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Interaction of C3–C5 Alkenes with Zeolitic Brønsted Sites: π-Complexes, Alkoxides, and Carbenium Ions in H-FER, J. Phys. Chem. C 124 (2020) 10067-10078
Q. Ren, M. Rybicki, J. Sauer
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Chemically Accurate Vibrational Free Energies of Adsorption from DFT Molecular Dynamics: Alkanes in Zeolites, J. Chem. Theory and Comput. 17 (2021) 5849-5862
D. Galimberti, J. Sauer
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Rigid Body Approximation for the Anharmonic Description of Molecule–Surface Vibrations, J. Chem. Theory and Comput.
M. Rybicki, J. Sauer
