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Liu C, Aguirre NF, Cawkwell MJ, Batista ER, Yang P. Efficient Parameterization of Density Functional Tight-Binding for 5 f-Elements: A Th-O Case Study. J Chem Theory Comput 2024; 20:5923-5936. [PMID: 38990696 PMCID: PMC11270830 DOI: 10.1021/acs.jctc.4c00145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 06/23/2024] [Accepted: 06/26/2024] [Indexed: 07/13/2024]
Abstract
Density functional tight binding (DFTB) models for f-element species are challenging to parametrize owing to the large number of adjustable parameters. The explicit optimization of the terms entering the semiempirical DFTB Hamiltonian related to f orbitals is crucial to generating a reliable parametrization for f-block elements, because they play import roles in bonding interactions. However, since the number of parameters grows quadratically with the number of orbitals, the computational cost for parameter optimization is much more expensive for the f-elements than for the main group elements. In this work we present a set of efficient approaches for mitigating the hurdle imposed by the large size of the parameter space. A novel group-by-orbital correction functions for two-center bond integrals was developed. With this approach the number of parameters is reduced, and it grows linearly with the number of elements, maintaining the accuracy and the number of parameters, in the case of f elements, by more than 40%. The parameter optimization step was accelerated by means of the mini-batch BFGS method. This method allows parameter optimizations with much larger training sets than other single batch methods. A stochastic optimizer was employed that helped overcome shallow local minima in the objective function. The proposed algorithm was used to parametrize the DFTB Hamiltonian for the Th-O system, which was subsequently applied to the study of ThO2 nanoparticles. The training set consisted of 6322 unique structures, which is barely feasible with conventional optimization methods. The optimized parameter set, LANL-ThO, displays good agreement with DFT-calculated properties such as energies, forces, and structures for both clusters and bulk ThO2. Benefiting from the fewer number of parameters and lower computational costs for objective function evaluations, this new approach shows its potential applications in DFTB parametrization for elements with high angular momentum, which present a challenge to conventional methods.
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Affiliation(s)
- Chang Liu
- Theoretical Division, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Néstor F. Aguirre
- Theoretical Division, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Marc J. Cawkwell
- Theoretical Division, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique R. Batista
- Theoretical Division, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
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Cawkwell MJ, Manner VW. Properties of Erythritol Tetranitrate from Molecular Dynamics Simulation. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2024; 128:5749-5758. [PMID: 38595775 PMCID: PMC11000242 DOI: 10.1021/acs.jpcc.4c00489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 04/11/2024]
Abstract
The nonpolarizable force field for alkyl nitrates developed by Borodin et al. [J. Phys. Chem. B, 2008, 112, 734-742] has been employed to calculate selected properties of crystalline and liquid erythritol tetranitrate (ETN). The set of partial charges proposed by Borodin for pentaerythritol tetranitrate (PETN) was used except for a small correction to the H atom charges to ensure charge neutrality owing to the absence of the neopentyl carbon in ETN. The force field was used to compute the isothermal compression curve, lattice parameters, heat capacity, thermal expansivity, single crystal elastic constants, and Gruneisen parameters of crystalline ETN. The density- and temperature-dependent viscosities of liquid ETN are also reported. We anticipate that these data will be of some utility to the development of equations of state and thermomechanical models for ETN.
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Affiliation(s)
- M. J. Cawkwell
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - V. W. Manner
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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3
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Marrs FW, Davis JV, Burch AC, Brown GW, Lease N, Huestis PL, Cawkwell MJ, Manner VW. Chemical Descriptors for a Large-Scale Study on Drop-Weight Impact Sensitivity of High Explosives. J Chem Inf Model 2023; 63:753-769. [PMID: 36695777 PMCID: PMC9930127 DOI: 10.1021/acs.jcim.2c01154] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Indexed: 01/26/2023]
Abstract
The drop-weight impact test is an experiment that has been used for nearly 80 years to evaluate handling sensitivity of high explosives. Although the results of this test are known to have large statistical uncertainties, it is one of the most common tests due to its accessibility and modest material requirements. In this paper, we compile a large data set of drop-weight impact sensitivity test results (mainly performed at Los Alamos National Laboratory), along with a compendium of molecular and chemical descriptors for the explosives under test. These data consist of over 500 unique explosives, over 1000 repeat tests, and over 100 descriptors, for a total of about 1500 observations. We use random forest methods to estimate a model of explosive handling sensitivity as a function of chemical and molecular properties of the explosives under test. Our model predicts well across a wide range of explosive types, spanning a broad range of explosive performance and sensitivity. We find that properties related to explosive performance, such as heat of explosion, oxygen balance, and functional group, are highly predictive of explosive handling sensitivity. Yet, models that omit many of these properties still perform well. Our results suggest that there is not one or even several factors that explain explosive handling sensitivity, but that there are many complex, interrelated effects at play.
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Affiliation(s)
- Frank W. Marrs
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Jack V. Davis
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Alexandra C. Burch
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Geoffrey W. Brown
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Nicholas Lease
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | | | - Marc J. Cawkwell
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
| | - Virginia W. Manner
- Los Alamos National Laboratory, Los Alamos, New Mexico87545, United States
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Zhou Z, Qiu Q. Molecular insights into the compression response of nitrogen / tetrafluoromethane liquid mixture from ab initio molecular dynamics. J Mol Liq 2023. [DOI: 10.1016/j.molliq.2023.121359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Cawkwell MJ, Davis J, Lease N, Marrs FW, Burch A, Ferreira S, Manner VW. Understanding Explosive Sensitivity with Effective Trigger Linkage Kinetics. ACS PHYSICAL CHEMISTRY AU 2022; 2:448-458. [PMID: 36855691 PMCID: PMC9955191 DOI: 10.1021/acsphyschemau.2c00022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We present a simple linear model for ranking the drop weight impact sensitivity of organic explosives that is based explicitly on chemical kinetics. The model is parameterized to specific heats of explosion, Q, and Arrhenius kinetics for the onset of chemical reactions that are obtained from gas-phase Born-Oppenheimer molecular dynamics simulations for a chemically diverse set of 24 molecules. Reactive molecular dynamics simulations sample all possible decomposition pathways of the molecules with the appropriate probabilities to provide an effective reaction barrier. In addition, the calculations of effective trigger linkage kinetics can be accomplished without prior physical intuition of the most likely decomposition pathways. We found that the specific heat of explosion tends to reduce the effective barrier for decomposition in accordance with the Bell-Evans-Polanyi principle, which accounts naturally for the well-known correlations between explosive performance and sensitivity. Our model indicates that sensitive explosives derive their properties from a combination of weak trigger linkages that react at relatively low temperatures and large specific heats of explosion that further reduce the effective activation energy.
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6
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Cawkwell MJ, Burch AC, Ferreira SR, Lease N, Manner VW. Atom Equivalent Energies for the Rapid Estimation of the Heat of Formation of Explosive Molecules from Density Functional Tight Binding Theory. J Chem Inf Model 2021; 61:3337-3347. [PMID: 34252276 DOI: 10.1021/acs.jcim.1c00312] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Atom equivalent energies have been derived from which the gas-phase heat of formation of explosive molecules can be estimated from fast, semiempirical density functional tight binding total energy calculations. The root-mean-square deviation and maximum deviation of the heats of formation from the experimental values for the set of 45 energetic molecules compiled by Byrd and Rice [ J. Phys. Chem. A, 2006, 110, 1005-1013] are 10.4 and 25.5 kcal/mol, respectively, using 4 atom equivalent energies and 7.4 and 15.0 kcal/mol, respectively, using 7 atom equivalent energies. These errors are around a factor of 2-3 larger than those obtained from density functional theory calculations but are smaller than those obtained from other semiempirical electronic structure methods. Heats of formation calculated with density functional tight binding theory using the 4 and 7 atom equivalent energies, the Byrd and Rice scheme, and the atom pair contribution method for a new set of 531 energetic molecules that contain only carbon, hydrogen, nitrogen, and oxygen are provided.
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Affiliation(s)
- Marc J Cawkwell
- Los Alamos National Laboratory, Mail Stop B221 Los Alamos, New Mexico 87545, United States
| | - Alexandra C Burch
- Los Alamos National Laboratory, Mail Stop B221 Los Alamos, New Mexico 87545, United States
| | - Suyana R Ferreira
- Los Alamos National Laboratory, Mail Stop B221 Los Alamos, New Mexico 87545, United States
| | - Nicholas Lease
- Los Alamos National Laboratory, Mail Stop B221 Los Alamos, New Mexico 87545, United States
| | - Virginia W Manner
- Los Alamos National Laboratory, Mail Stop B221 Los Alamos, New Mexico 87545, United States
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Carlson RK, Cawkwell MJ, Batista ER, Yang P. Tight-Binding Modeling of Uranium in an Aqueous Environment. J Chem Theory Comput 2020; 16:3073-3083. [DOI: 10.1021/acs.jctc.0c00089] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rebecca K. Carlson
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - M. J. Cawkwell
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique R. Batista
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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Perriot R, Cawkwell MJ, Martinez E, McGrane SD. Reaction Rates in Nitromethane under High Pressure from Density Functional Tight Binding Molecular Dynamics Simulations. J Phys Chem A 2020; 124:3314-3328. [DOI: 10.1021/acs.jpca.9b11897] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Romain Perriot
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - M. J. Cawkwell
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique Martinez
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Shawn D. McGrane
- Shock and Detonation Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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9
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Aguirre NF, Morgenstern A, Cawkwell MJ, Batista ER, Yang P. Development of Density Functional Tight-Binding Parameters Using Relative Energy Fitting and Particle Swarm Optimization. J Chem Theory Comput 2020; 16:1469-1481. [DOI: 10.1021/acs.jctc.9b00880] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Néstor F. Aguirre
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Amanda Morgenstern
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - M. J. Cawkwell
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Enrique R. Batista
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Ping Yang
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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10
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Cawkwell MJ, Manner VW. Ranking the Drop-Weight Impact Sensitivity of Common Explosives Using Arrhenius Chemical Rates Computed from Quantum Molecular Dynamics Simulations. J Phys Chem A 2019; 124:74-81. [DOI: 10.1021/acs.jpca.9b10808] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- M. J. Cawkwell
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
| | - V. W. Manner
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States
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11
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Martínez E, Perriot R, Kober EM, Bowlan P, Powell M, McGrane S, Cawkwell MJ. Parallel replica dynamics simulations of reactions in shock compressed liquid benzene. J Chem Phys 2019; 150:244108. [PMID: 31255087 DOI: 10.1063/1.5092209] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The study of the long-term evolution of slow chemical reactions is challenging because quantum-based reactive molecular dynamics simulation times are typically limited to hundreds of picoseconds. Here, the extended Lagrangian Born-Oppenheimer molecular dynamics formalism is used in conjunction with parallel replica dynamics to obtain an accurate tool to describe the long-term chemical dynamics of shock-compressed benzene. Langevin dynamics has been employed at different temperatures to calculate the first reaction times in liquid benzene at pressures and temperatures consistent with its unreacted Hugoniot. Our coupled engine runs for times on the order of nanoseconds (one to two orders of magnitude longer than traditional techniques) and is capable of detecting reactions that are characterized by rates significantly slower than we could study before. At lower pressures and temperatures, we mainly observe Diels-Alder metastable reactions, whereas at higher pressures and temperatures we observe stable polymerization reactions.
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Affiliation(s)
- E Martínez
- Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - R Perriot
- Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - E M Kober
- Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P Bowlan
- Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M Powell
- Shock and Detonation Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - S McGrane
- Shock and Detonation Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M J Cawkwell
- Theoretical Division, T-1, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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12
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Bowlan P, Powell M, Perriot R, Martinez E, Kober EM, Cawkwell MJ, McGrane S. Probing ultrafast shock-induced chemistry in liquids using broad-band mid-infrared absorption spectroscopy. J Chem Phys 2019; 150:204503. [DOI: 10.1063/1.5092242] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Pamela Bowlan
- Physical Chemistry and Applied Spectroscopy, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Michael Powell
- Shock and Detonation Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
- Maurice J. Zucrow Laboratory, Mechanical Engineering Department, Purdue University, 500 Allison Rd., West Lafayette, Indiana 47907, USA
| | - Romain Perriot
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Enrique Martinez
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Edward M. Kober
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M. J. Cawkwell
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Shawn McGrane
- Shock and Detonation Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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