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Fortenberry RC. Picking up Good Vibrations through Quartic Force Fields and Vibrational Perturbation Theory. J Phys Chem Lett 2024; 15:6528-6537. [PMID: 38875074 DOI: 10.1021/acs.jpclett.4c01089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Quartic force fields (QFFs) define sparse potential energy surfaces (compared to semiglobal surfaces) that are the cheapest and easiest means of computing anharmonic vibrational frequencies, especially when utilized with second-order vibrational perturbation theory (VPT2). However, flat and shallow potential surfaces are exceedingly difficult for QFFs to treat through a combination of numerical noise in the often numerically computed derivatives and in competing energy factors in the composite energies often utilized to provide high-level spectroscopic predictions. While some of these issues can be alleviated with analytic derivatives, hybrid QFFs, and intelligent choices in coordinate systems, the best practice is for predicting good molecular vibrations via QFFs is to understand what they cannot do, and this manuscript documents such cases where QFFs may fail.
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Affiliation(s)
- Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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Abstract
pbqff is an open-source program for fully automating the production of quartic force fields (QFFs) and their corresponding anharmonic spectroscopic data. Rather than being a monolithic piece of code, it consists of several key modules including a generic interface to quantum chemistry codes and, notably, queuing systems; a molecular point group symmetry library; an internal-to-Cartesian coordinate conversion module; a module for the ordinary least-squares fitting of potential energy surfaces; and an improved second-order rotational and vibrational perturbation theory package for asymmetric and symmetric tops that handles type-1 and -2 Fermi resonances, Fermi resonance polyads, and Coriolis resonances. All of these pieces are written in Rust, a modern, safe, and performant programming language that has much to offer for scientific programming. This work introduces pbqff and its surrounding ecosystem, in addition to reporting new anharmonic vibrational data for c-(C)C3H2 and describing how the components of pbqff can be leveraged in other projects.
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Affiliation(s)
- Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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Schleier D, Gerlach M, Pratim Mukhopadhyay D, Karaev E, Schaffner D, Hemberger P, Fischer I. Ammonia Borane, NH 3 BH 3 : A Threshold Photoelectron-Photoion Coincidence Study of a Potential Hydrogen-Storage Material. Chemistry 2022; 28:e202201378. [PMID: 35622451 PMCID: PMC9401591 DOI: 10.1002/chem.202201378] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Indexed: 12/17/2022]
Abstract
We have investigated the photoionization of ammonia borane (AB) and determined adiabatic ionization energy to be 9.26±0.03 eV for the X+ 2E←X 1A1 transition. Although the threshold photoelectron spectrum appears at first glance to be similar to the one of the isosteric ethane, the electronic situation differs markedly, due to different orbital energies. In addition, an appearance energy AE0K(NH3BH3, NH3BH2+)= 10.00±0.03 eV has been determined, corresponding to the loss of a hydrogen atom at the BH3‐site. From the data, a 0 K bond dissociation energy for the B−H bond in the cation of 71.5±3 kJ mol−1 was derived, whereas the one in the neutral compound has been estimated to be 419±10 kJ mol−1.
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Affiliation(s)
- Domenik Schleier
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.,Present Address: Laboratory for Astrophysics, Leiden Observatory, Leiden University, 2300 RA, Leiden (The, Netherlands
| | - Marius Gerlach
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Deb Pratim Mukhopadhyay
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.,Present address: Department of Dynamics of Molecules and Clusters, J. Heyrovský Institute of Physical Chemistry, Dolejškova 2155/3, 182 23, Praha 8, Czech Republic
| | - Emil Karaev
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Dorothee Schaffner
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Patrick Hemberger
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institut (PSI), 5232, Villigen, Switzerland
| | - Ingo Fischer
- Institute of Physical and Theoretical Chemistry, University of Würzburg, Am Hubland, 97074, Würzburg, Germany
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Westbrook B, Beasley G, Fortenberry RC. Polycyclic Aliphatic Hydrocarbons: Is Tetrahedrane Present in UIR Spectra? Phys Chem Chem Phys 2022; 24:14348-14353. [DOI: 10.1039/d2cp01103d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The smallest Platonic hydrocarbon, tetrahedrane, has been subject to frequent theoretical and experimental study for 50 years, but its infrared spectrum and synthetic pathway remain a mystery. The recent partial...
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Watrous AG, Westbrook BR, Fortenberry RC. F12-TZ-cCR: A Methodology for Faster and Still Highly Accurate Quartic Force Fields. J Phys Chem A 2021; 125:10532-10540. [PMID: 34846883 DOI: 10.1021/acs.jpca.1c08355] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The F12-TZ-cCR quartic force field (QFF) methodology, defined here as CCSD(T)-F12b/cc-pCVTZ-F12 with further corrections for relativity, is introduced as a cheaper and even more accurate alternative to more costly composite QFF methods like those containing complete basis set extrapolations within canonical coupled cluster theory. F12-TZ-cCR QFFs produce B0 and C0 vibrationally averaged principal rotational constants within 7.5 MHz of gas-phase experimental values for tetraatomic and larger molecules, offering higher accuracy in these constants than the previous composite methods. In addition, F12-TZ-cCR offers an order of magnitude decrease in the computational cost of highly accurate QFF methodologies accompanying this increase in accuracy. An additional order of magnitude in cost reduction is achieved in the F12-DZ-cCR method, while also matching the accuracy of the traditional composite method's B0 and C0 constants. Finally, F12-DZ and F12-TZ are benchmarked on the same test set, revealing that both methods can provide anharmonic vibrational frequencies that are comparable in accuracy to all three of the more expensive methodologies, although their rotational constants lag behind. Hence, the present work demonstrates that highly accurate theoretical rovibrational spectral data can be obtained for a fraction of the cost of conventional QFF methodologies, extending the applicability of QFFs to larger molecules.
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Affiliation(s)
- Alexandria G Watrous
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Brent R Westbrook
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
| | - Ryan C Fortenberry
- Department of Chemistry & Biochemistry, University of Mississippi, University, Mississippi 38677-1848, United States
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Westbrook BR, Fortenberry RC. Anharmonic Vibrational Frequencies of Water Borane and Associated Molecules. Molecules 2021; 26:molecules26237348. [PMID: 34885929 PMCID: PMC8658819 DOI: 10.3390/molecules26237348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/26/2021] [Accepted: 11/29/2021] [Indexed: 12/03/2022] Open
Abstract
Water borane (BH3OH2) and borinic acid (BH2OH) have been proposed as intermediates along the pathway of hydrogen generation from simple reactants: water and borane. However, the vibrational spectra for neither water borane nor borinic acid has been investigaged experimentally due to the difficulty of isolating them in the gas phase, making accurate quantum chemical predictions for such properties the most viable means of their determination. This work presents theoretical predictions of the full rotational and fundamental vibrational spectra of these two potentially application-rich molecules using quartic force fields at the CCSD(T)-F12b/cc-pCVTZ-F12 level with additional corrections included for the effects of scalar relativity. This computational scheme is further benchmarked against the available gas-phase experimental data for the related borane and HBO molecules. The differences are found to be within 3 cm−1 for the fundamental vibrational frequencies and as close as 15 MHz in the B0 and C0 principal rotational constants. Both BH2OH and BH3OH2 have multiple vibrational modes with intensities greater than 100 km mol−1, namely ν2 and ν4 in BH2OH, and ν1, ν3, ν4, ν9, and ν13 in BH3OH2. Finally, BH3OH2 has a large dipole moment of 4.24 D, which should enable it to be observable by rotational spectroscopy, as well.
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Lin CK, Huang QR, Hayashi M, Kuo JL. An ab initio anharmonic approach to IR, Raman and SFG spectra of the solvated methylammonium ion. Phys Chem Chem Phys 2021; 23:25736-25747. [PMID: 34755745 DOI: 10.1039/d1cp04451f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The methylammonium ion (CH3NH3+, or noted as MA-H+) is one of the smallest organic ammonium ions that play important roles in organic-inorganic halide perovskites. Despite the simple structure, the vibrational spectra of MA-H+ exhibit complicated features in the 3 μm region which are sensitive to the solvation environment. In the present work, we have applied the ab initio anharmonic algorithm at the CCSD/aug-cc-pVDZ level to simulate the IR and Raman spectra of the solvated methylammonium ion, MA-H+⋯X3, where X denotes the solvent molecules, to understand the Fermi resonance mechanism in which the overtones of NH bending modes are coupled with the fundamentals of NH stretching modes. The spectral features of the solvated clusters with proper solvent species resemble those observed in the perovskite crystal, indicating that they have similar solvation environments and hydrogen bond interactions. Therefore, a linkage between the gas-phase cluster models and the condensed-phase materials can be established, and our simulations and anharmonic analyses help in interpreting the spectral assignments of the observed IR and Raman spectra of perovskites reliably. Furthermore, we have extended this approach to the SFG spectra to demonstrate the selective appearance of bands depending on both the beam polarization configurations and the symmetry of vibrational modes.
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Affiliation(s)
- Chih-Kai Lin
- Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan, Republic of China.
| | - Qian-Rui Huang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan, Republic of China.
| | - Michitoshi Hayashi
- Center for Condensed Matter Sciences, National Taiwan University, Taipei, 10617, Taiwan, Republic of China
| | - Jer-Lai Kuo
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan, Republic of China.
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Lyu Z, Sun S, Wu T. Highly stretchable covalent adaptive networks enabled by dynamic boronic diester linkages with nitrogen→boron coordination. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210706] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Zhenyu Lyu
- Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices School of Materials Science and Engineering, Sun Yat‐sen University Guangzhou China
| | - Shiqi Sun
- Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices School of Materials Science and Engineering, Sun Yat‐sen University Guangzhou China
| | - Tongfei Wu
- Guangzhou Key Laboratory of Flexible Electronic Materials and Wearable Devices School of Materials Science and Engineering, Sun Yat‐sen University Guangzhou China
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Rossi M. Progress and challenges in ab initio simulations of quantum nuclei in weakly bonded systems. J Chem Phys 2021; 154:170902. [PMID: 34241065 DOI: 10.1063/5.0042572] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Atomistic simulations based on the first-principles of quantum mechanics are reaching unprecedented length scales. This progress is due to the growth in computational power allied with the development of new methodologies that allow the treatment of electrons and nuclei as quantum particles. In the realm of materials science, where the quest for desirable emergent properties relies increasingly on soft weakly bonded materials, such methods have become indispensable. In this Perspective, an overview of simulation methods that are applicable for large system sizes and that can capture the quantum nature of electrons and nuclei in the adiabatic approximation is given. In addition, the remaining challenges are discussed, especially regarding the inclusion of nuclear quantum effects (NQEs) beyond a harmonic or perturbative treatment, the impact of NQEs on electronic properties of weakly bonded systems, and how different first-principles potential energy surfaces can change the impact of NQEs on the atomic structure and dynamics of weakly bonded systems.
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Affiliation(s)
- Mariana Rossi
- Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
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