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Kroonblawd MP, Goldman N, Maiti A, Lewicki JP. Polymer degradation through chemical change: a quantum-based test of inferred reactions in irradiated polydimethylsiloxane. Phys Chem Chem Phys 2022; 24:8142-8157. [PMID: 35332907 DOI: 10.1039/d1cp05647f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Chemical reaction schemes are key conceptual tools for interpreting the results of experiments and simulations, but often carry implicit assumptions that remain largely unverified for complicated systems. Established schemes for chemical damage through crosslinking in irradiated silicone polymers comprised of polydimethylsiloxane (PDMS) date to the 1950's and correlate small-molecule off-gassing with specific crosslink features. In this regard, we use a somewhat reductionist model to develop a general conditional probability and correlation analysis approach that tests these types of causal connections between proposed experimental observables to reexamine this chemistry through quantum-based molecular dynamics (QMD) simulations. Analysis of the QMD simulations suggests that the established reaction schemes are qualitatively reasonable, but lack strong causal connections under a broad set of conditions that would enable making direct quantitative connections between off-gassing and crosslinking. Further assessment of the QMD data uncovers a strong (but nonideal) quantitative connection between exceptionally hard-to-measure chain scission events and the formation of silanol (Si-OH) groups. Our analysis indicates that conventional notions of radiation damage to PDMS should be further qualified and not necessarily used ad hoc. In addition, our efforts enable independent quantum-based tests that can inform confidence in assumed connections between experimental observables without the burden of fully elucidating entire reaction networks.
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Affiliation(s)
- Matthew P Kroonblawd
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
| | - Nir Goldman
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
| | - Amitesh Maiti
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
| | - James P Lewicki
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
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Lehtola S. Straightforward and Accurate Automatic Auxiliary Basis Set Generation for Molecular Calculations with Atomic Orbital Basis Sets. J Chem Theory Comput 2021; 17:6886-6900. [PMID: 34614349 DOI: 10.1021/acs.jctc.1c00607] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Density fitting (DF), also known as the resolution of the identity (RI), is a widely used technique in quantum chemical calculations with various types of atomic basis sets─Gaussian-type orbitals, Slater-type orbitals, as well as numerical atomic orbitals─to speed up density functional, Hartree-Fock (HF), and post-HF calculations. Traditionally, custom auxiliary basis sets are hand-optimized for each orbital basis set; however, some automatic schemes have also been suggested. In this work, we propose a simple yet numerically stable automated scheme for forming auxiliary basis sets with the help of a pivoted Cholesky decomposition, which is applicable to any type of atomic basis function. We exemplify the scheme with proof-of-concept calculations with Gaussian basis sets and show that the proposed approach leads to negligible DF/RI errors in HF and second-order Møller-Plesset (MP2) total energies of the non-multireference part of the W4-17 test set when used with orbital basis sets of at least polarized triple-ζ quality. The results are promising for future applications employing Slater-type orbitals or numerical atomic orbitals, as well as schemes based on the use of local fitting approaches. Global fitting approaches can also be used, in which case the high-angular-momentum functions produced by the present scheme can be truncated to minimize the computational cost.
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Affiliation(s)
- Susi Lehtola
- Molecular Sciences Software Institute, Blacksburg, Virginia 24061, United States
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Koskelo J, Juurinen I, Ruotsalainen KO, McGrath MJ, Kuo IF, Lehtola S, Galambosi S, Hämäläinen K, Huotari S, Hakala M. Intra- and intermolecular effects on the Compton profile of the ionic liquid 1,3-dimethylimidazolium chloride. J Chem Phys 2014; 141:244505. [PMID: 25554165 DOI: 10.1063/1.4904278] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present a comprehensive simulation study on the solid-liquid phase transition of the ionic liquid 1,3-dimethylimidazolium chloride in terms of the changes in the atomic structure and their effect on the Compton profile. The structures were obtained by using ab initio molecular dynamics simulations. Chosen radial distribution functions of the liquid structure are presented and found generally to be in good agreement with previous ab initio molecular dynamics and neutron scattering studies. The main contributions to the predicted difference Compton profile are found to arise from intermolecular changes in the phase transition. This prediction can be used for interpreting future experiments.
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Affiliation(s)
- J Koskelo
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - I Juurinen
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - K O Ruotsalainen
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - M J McGrath
- Laboratoire des Sciences du Climat et de l'Environnement, CEA-Orme des Merisiers, F-91191 Gif-sur-Yvette CEDEX, France
| | - I-F Kuo
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - S Lehtola
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - S Galambosi
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - K Hämäläinen
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - S Huotari
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - M Hakala
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
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Juurinen I, Galambosi S, Anghelescu-Hakala AG, Koskelo J, Honkimäki V, Hämäläinen K, Huotari S, Hakala M. Molecular-Level Changes of Aqueous Poly(N-isopropylacrylamide) in Phase Transition. J Phys Chem B 2014; 118:5518-23. [DOI: 10.1021/jp501913p] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Iina Juurinen
- Department
of Physics, University of Helsinki, P.O.B. 64, FI-00014, Helsinki, Finland
| | - Szabolcs Galambosi
- Department
of Physics, University of Helsinki, P.O.B. 64, FI-00014, Helsinki, Finland
| | - Adina G. Anghelescu-Hakala
- VTT Technical Research Centre of Finland, Patruunantie 19, FI-05200, Rajamäki, Finland
- Department
of Chemistry, Laboratory of Polymer Chemistry, University of Helsinki, P.O.B. 55, FI-00014, Helsinki, Finland
| | - Jaakko Koskelo
- Department
of Physics, University of Helsinki, P.O.B. 64, FI-00014, Helsinki, Finland
| | - Veijo Honkimäki
- European Synchrotron Radiation Facility, F-38043, Grenoble Cedex 9, France
| | - Keijo Hämäläinen
- Department
of Physics, University of Helsinki, P.O.B. 64, FI-00014, Helsinki, Finland
| | - Simo Huotari
- Department
of Physics, University of Helsinki, P.O.B. 64, FI-00014, Helsinki, Finland
| | - Mikko Hakala
- Department
of Physics, University of Helsinki, P.O.B. 64, FI-00014, Helsinki, Finland
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Lehtola S, Manninen P, Hakala M, Hämäläinen K. Contraction of completeness-optimized basis sets: Application to ground-state electron momentum densities. J Chem Phys 2013; 138:044109. [DOI: 10.1063/1.4788635] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Susi Lehtola
- Department of Physics, University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland.
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Lehtola J, Manninen P, Hakala M, Hämäläinen K. Completeness-optimized basis sets: Application to ground-state electron momentum densities. J Chem Phys 2012; 137:104105. [DOI: 10.1063/1.4749272] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Lehtola J, Hakala M, Sakko A, Hämäläinen K. ERKALE-A flexible program package for X-ray properties of atoms and molecules. J Comput Chem 2012; 33:1572-85. [DOI: 10.1002/jcc.22987] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 02/02/2012] [Accepted: 03/16/2012] [Indexed: 02/04/2023]
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Erba A, Pisani C. Evaluation of the electron momentum density of crystalline systems from ab initio linear combination of atomic orbitals calculations. J Comput Chem 2012; 33:822-31. [DOI: 10.1002/jcc.22907] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 10/24/2011] [Accepted: 11/16/2011] [Indexed: 11/08/2022]
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