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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Using Density Functional Theory (DFT) for the Calculation of Atomization Energies

The calculation of atomization energies using density functional theory (DFT), using the B3LYP hybrid functional, is reported. The sensitivity of the atomization energy to basis set is studied and compared with the coupled cluster singles and doubles approach with a perturbational estimate of the triples (CCSD(T)). Merging the B3LYP results with the G2(MP2) approach is also considered. It is found that replacing the geometry optimization and calculation of the zero-point energy by the analogous quantities computed using the B3LYP approach reduces the maximum error in the G2(MP2) approach. In addition to the 55 G2 atomization energies, some results for transition metal containing systems will also be presented.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1992

On the performance of large Gaussian basis sets for the computation of total atomization energies

The total atomization energies of a number of molecules have been computed using an augmented coupled-cluster method and (5s4p3d2f1g) and 4s3p2d1f) atomic natural orbital (ANO) basis sets, as well as the correlation consistent valence triple zeta plus polarization (cc-pVTZ) correlation consistent valence quadrupole zeta plus polarization (cc-pVQZ) basis sets. The performance of ANO and correlation consistent basis sets is comparable throughout, although the latter can result in significant CPU time savings. Whereas the inclusion of g functions has significant effects on the computed Sigma D(e) values, chemical accuracy is still not reached for molecules involving multiple bonds. A Gaussian-1 (G) type correction lowers the error, but not much beyond the accuracy of the G1 model itself. Using separate corrections for sigma bonds, pi bonds, and valence pairs brings down the mean absolute error to less than 1 kcal/mol for the spdf basis sets, and about 0.5 kcal/mol for the spdfg basis sets. Some conclusions on the success of the Gaussian-1 and Gaussian-2 models are drawn.

Martin, J. M. L.↗
NASA NTRS1999

The Atomization Energy of Mg4

The atomization energy of Mg4 is determined using the MP2 and CCSD(T) levels of theory. Basis set incompleteness, basis set extrapolation, and core-valence effects are discussed. Our best atomization energy, including the zero-point energy and scalar relativistic effects, is 24.6+/-1.6 kcal per mol. Our computed and extrapolated values are compared with previous results, where it is observed that our extrapolated MP2 value is good agreement with the MP2-R12 value. The CCSD(T) and MP2 core effects are found to have the opposite signs.

Bauschlicher, Charles W., Jr.↗
DOE OSTI2025

Atomic Energy Accuracy of Neural Network Potentials: Harnessing Pretraining and Transfer Learning

Machine learning-based interatomic potentials (MLIPs) have transformed the prediction of potential energy surfaces (PESs), achieving accuracy comparable to ab initio calculations. However, atomic energy predictions, often assumed to lack physical meaning, remain underexplored. In this study, we demonstrate that inaccuracies in atomic energy predictions reduce the robustness and transferability of Neural Network Potentials (NNPs) and atomic energy error can be masked in total energy predictions due to error cancellation. Here, we validate this finding using challenging configurations involving deformation and failure under tensile loading. By pretraining atomic energy predictions using empirical potentials and applying transfer learning with density functional theory (DFT) data, we achieve notable improvements in the accuracy of total energy, forces, and stress predictions. Furthermore, this approach enhances the robustness and transferability of NNPs, emphasizing the importance of atomic energy predictions in developing high-quality and reliable MLIPs.

Active Learning↗
NASA NTRS1995

The Sensitivity of B3LYP Atomization Energies to the Basis Set and a Comparison of the Basis Set Requirements for CCSD(T) and B3LYP

The atomization energies of the 55 G2 molecules are computed using the B3LYP approach with a variety of basis sets. The 6-311 + G(3df) basis set is found to yield superior results to those obtained using the augmented - correlation - consistent valence-polarized triple-zeta set. The atomization energy of SO2 is found to be the most sensitive to basis set and is studied in detail. Including tight d functions is found to be important for obtaining good atomization energies. The results for SO2 are compared with those obtained using the coupled-cluster singles and doubles approach including a perturbational estimate of the triple excitations.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1998

Atomization Energies of SO and SO2; Basis Set Extrapolation Revisted

The addition of tight functions to sulphur and extrapolation to the complete basis set limit are required to obtain accurate atomization energies. Six different extrapolation procedures are tried. The best atomization energies come from the series of basis sets that yield the most consistent results for all extrapolation techniques. In the variable alpha approach, alpha values larger than 4.5 or smaller than 3, appear to suggest that the extrapolation may not be reliable. It does not appear possible to determine a reliable basis set series using only the triple and quadruple zeta based sets. The scalar relativistic effects reduce the atomization of SO and SO2 by 0.34 and 0.81 kcal/mol, respectively, and clearly must be accounted for if a highly accurate atomization energy is to be computed. The magnitude of the core-valence (CV) contribution to the atomization is affected by missing diffuse valence functions. The CV contribution is much more stable if basis set superposition errors are accounted for. A similar study of SF, SF(+), and SF6 shows that the best family of basis sets varies with the nature of the S bonding.

Bauschlicher, Charles W., Jr.↗
NASA NTRS2011

Attenuation of Scattered Thermal Energy Atomic Oxygen

The attenuation of scattered thermal energy atomic oxygen is relevant to the potential damage that can occur within a spacecraft which sweeps through atomic oxygen in low Earth orbit (LEO). Although there can be significant oxidation and resulting degradation of polymers and some metals on the external surfaces of spacecraft, there are often openings on a spacecraft such as telescope apertures, vents, and microwave cavities that can allow atomic oxygen to enter and scatter internally to the spacecraft. Atomic oxygen that enters a spacecraft can thermally accommodate and scatter to ultimately react or recombine on surfaces. The atomic oxygen that does enter a spacecraft can be scavenged by use of high erosion yield polymers to reduce its reaction on critical surfaces and materials. Polyoxymethylene and polyethylene can be used as effective atomic oxygen scavenging polymers.

Banks, Bruce a.↗
NASA NTRS2011

Attenuation of Scattered Thermal Energy Atomic Oxygen

The attenuation of scattered thermal energy atomic oxygen is relevant to the potential damage that can occur within a spacecraft which sweeps through atomic oxygen in low Earth orbit (LEO). Although there can be significant oxidation and resulting degradation of polymers and some metals on the external surfaces of spacecraft, there are often openings on a spacecraft such as telescope apertures, vents, and microwave cavities that can allow atomic oxygen to enter and scatter internally to the spacecraft. Atomic oxygen that enters a spacecraft can thermally accommodate and scatter to ultimately react or recombine on surfaces. The atomic oxygen that does enter a spacecraft can be scavenged by use of high erosion yield polymers to reduce its reaction on critical surfaces and materials. Polyoxymethylene and polyethylene can be used as effective atomic oxygen scavenging polymers.

Banks, Bruce A.↗
DOE OSTI2026

Justification that the Thermo-Fisher Scientific 241 Am Residues Were Generated by Atomic Energy Defense Activities

The Waste Isolation Pilot Plant (WIPP) Land Withdrawal Act (LWA) as amended by the National Defense Authorization Act for Fiscal Year 1997 (1) requires that for Transuranic (TRU) waste to be eligible for disposal at WIPP, it must have been generated by atomic energy defense activities. The definition of “atomic energy defense activity” is defined in the Nuclear Waste Policy Act of 1982 (NWPA) (2).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1974

Geothermal research and development program of the US Atomic Energy Commission

Within the overall federal geothermal program, the Atomic Energy Commission has chosen to concentrate on development of resource utilization and advanced research and technology as the areas most suitable to the expertise of its staff and that of the National Laboratories. The Commission's work in geothermal energy is coordinated with that of other agencies by the National Science Foundation, which has been assigned lead agency by the Office of Management and Budget. The objective of the Commission's program, consistent with the goals of the total federal program is to facilitate, through technological advancement and pilot plant operations, achievement of substantial commercial production of electrical power and utilization of geothermal heat by the year 1985. This will hopefully be accomplished by providing, in conjunction with industry, credible information on the economic operation and technological reliability of geothermal power and use of geothermal heat.

Werner, L. B.↗
DOE OSTI2023

Relativistic and magnetic Breit effects for the reaction Sg + 6CO → Sg(CO)6 and Sg(OC)6: Prediction of the existence and atomization energy of the isomer Sg(OC)6

Our ab initio all-electron fully relativistic Dirac–Fock (DF) and Dirac–Fock–Breit–Gaunt (DFBG) and nonrelativistic (NR) Hartree–Fock (HF) calculations for seaborgium hexacarbonyl Sg(CO)6 predict atomization energies (Ae) of 68.81, 69.28, and 67.69 eV, respectively, at the corresponding optimized octahedral geometry. However, our DF, DFBG, and NR HF calculations for the isomer Sg(OC)6 yield atomization energies of 64.30, 64.77, and 62.62 eV, respectively, at the optimized geometry for this species. The optimized Sg–C and C–O bond distances (in Å) for octahedral Sg(CO)6 using our DF (NR) calculations are 2.15 (2.32) and 1.11 (1.11), respectively. However, the optimized Sg–O and O–C bond distances (in Å) for the isomer octahedral Sg(OC)6 obtained with our DF (NR) calculations are 2.80 (2.73) and 1.10 (1.11), respectively. Our prediction of the greater stability of Sg(CO)6 isomer at both the relativistic (DF and DFBG) and the NR HF levels of theory lends further support to the detection of Sg(CO)6 in the state-of-the-art gas-phase experimental studies of the carbonyl complex of seaborgium reported by Even et al. [Science 345(6203), 1491 (2014)].

Materials Science↗
NASA NTRS2012

Observing Planets and Small Bodies in Sputtered High Energy Atom (SHEA) Fluxes

The evolution of the surfaces of bodies unprotected by either strong magnetic fields or thick atmospheres in the Solar System is caused by various processes, induced by photons, energetic ions and micrometeoroids. Among these processes, the continuous bombardment of the solar wind or energetic magnetospheric ions onto the bodies may significantly affect their surfaces, with implications for their evolution. Ion precipitation produces neutral atom releases into the exosphere through ion sputtering, with velocity distribution extending well above the particle escape limits. We refer to this component of the surface ejecta as sputtered high-energy atoms (SHEA). The use of ion sputtering emission for studying the interaction of exposed bodies (EB) with ion environments is described here. Remote sensing in SHEA in the vicinity of EB can provide mapping of the bodies exposed to ion sputtering action with temporal and mass resolution. This paper speculates on the possibility of performing remote sensing of exposed bodies using SHEA The evolution of the surfaces of bodies unprotected by either strong magnetic fields or thick atmospheres in the Solar System is caused by various processes, induced by photons, energetic ions and micrometeoroids. Among these processes, the continuous bombardment of the solar wind or energetic magnetospheric ions onto the bodies may significantly affect their surfaces, with implications for their evolution. Ion precipitation produces neutral atom releases into the exosphere through ion sputtering, with velocity distribution extending well above the particle escape limits. We refer to this component of the surface ejecta as sputtered high-energy atoms (SHEA). The use of ion sputtering emission for studying the interaction of exposed bodies (EB) with ion environments is described here. Remote sensing in SHEA in the vicinity of EB can provide mapping of the bodies exposed to ion sputtering action with temporal and mass resolution. This paper speculates on the possibility of performing remote sensing of exposed bodies using SHEA and suggests the need for quantitative results from laboratory simulations and molecular physic modeling in order to understand SHEA data from planetary missions. In the Appendix, referenced computer simulations using existing sputtering data are reviewed.

Milillo, A.↗
DOE OSTI2026

230 Th/ 234 U Model Age of International Atomic Energy Agency Sample 27107-14-04 Measured at Los Alamos National Laboratory

This report details the uranium age-dating of International Atomic Energy Agency (IAEA) bulk environmental cotton swipe sample 27107-14-04 at Los Alamos National Laboratory (LANL). The 230 Th/ 234 U radiochronometer was used to determine sample model age requiring the following analyses: U assay, U isotope composition, Th assay and Th isotope composition. Sample 27107-14-04 was received at LANL on November 3, 2025, along with cotton swipe blank 30124-24-20.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

J. Robert Oppenheimer: The Atomic Energy Commission and His Security Clearance, Selected Documents

On April 14, 1954, Laboratory employees were formally notified by a “Special Bulletin to All Employees” (Appendix A) that the Atomic Energy Commission had convened a Personnel Security Board, at the request of J. Robert Oppenheimer, to investigate “substantial derogatory information” about their former director. Long on procedural detail and short on specifics, the Bulletin served primarily as an announcement that “A board was accordingly established for the purpose of hearing the case and advising the Commission as to whether or not suspension of clearance of Dr. Oppenheimer should be made permanent.”

99 GENERAL AND MISCELLANEOUS↗
NASA NTRS1996

Prediction of In-Space Durability of Protected Polymers Based on Ground Laboratory Thermal Energy Atomic Oxygen

The probability of atomic oxygen reacting with polymeric materials is orders of magnitude lower at thermal energies (greater than O.1 eV) than at orbital impact energies (4.5 eV). As a result, absolute atomic oxygen fluxes at thermal energies must be orders of magnitude higher than orbital energy fluxes, to produce the same effective fluxes (or same oxidation rates) for polymers. These differences can cause highly pessimistic durability predictions for protected polymers and polymers which develop protective metal oxide surfaces as a result of oxidation if one does not make suitable calibrations. A comparison was conducted of undercut cavities below defect sites in protected polyimide Kapton samples flown on the Long Duration Exposure Facility (LDEF) with similar samples exposed in thermal energy oxygen plasma. The results of this comparison were used to quantify predicted material loss in space based on material loss in ground laboratory thermal energy plasma testing. A microindent hardness comparison of surface oxidation of a silicone flown on the Environmental Oxygen Interaction with Materials-III (EOIM-III) experiment with samples exposed in thermal energy plasmas was similarly used to calibrate the rate of oxidation of silicone in space relative to samples in thermal energy plasmas exposed to polyimide Kapton effective fluences.

Banks, Bruce A.↗