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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Tl(CO)2 by Materials Project

CTlCO2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is two-dimensional and consists of four ethyne molecules and two TlCO2 sheets oriented in the (0, 0, 1) direction. In each TlCO2 sheet, there are two inequivalent Tl3+ sites. In the first Tl3+ site, Tl3+ is bonded in a 3-coordinate geometry to three O2- atoms. There are a spread of Tl–O bond distances ranging from 2.67–2.84 Å. In the second Tl3+ site, Tl3+ is bonded in a 2-coordinate geometry to six O2- atoms. There are a spread of Tl–O bond distances ranging from 2.80–3.09 Å. There are two inequivalent C+0.50+ sites. In the first C+0.50+ site, C+0.50+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.27 Å) and one longer (1.28 Å) C–O bond length. In the second C+0.50+ site, C+0.50+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.27 Å) and one longer (1.28 Å) C–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to three Tl3+ and one C+0.50+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one Tl3+ and one C+0.50+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to three Tl3+ and one C+0.50+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Tl3+ and one C+0.50+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development of the tangent linear and adjoint models of the global online chemical transport model MPAS-CO 2 v7.3

We describe the development of the tangent linear (TL) and adjoint models of the Model for Prediction Across Scales (MPAS)-CO 2 transport model, which is a global online chemical transport model developed upon the non-hydrostatic Model for Prediction Across Scales – Atmosphere (MPAS-A). The primary goal is to make the model system a valuable research tool for investigating atmospheric carbon transport and inverse modeling. First, we develop the TL code, encompassing all CO 2 transport processes within the MPAS-CO 2 forward model. Then, we construct the adjoint model using a combined strategy involving re-calculation and storage of the essential meteorological variables needed for CO 2 transport. This strategy allows the adjoint model to undertake a long-period integration with moderate memory demands. To ensure accuracy, the TL and adjoint models undergo vigorous verifications through a series of standard tests. The adjoint model, through backward-in-time integration, calculates the sensitivity of atmospheric CO 2 observations to surface CO 2 fluxes and the initial atmospheric CO 2 mixing ratio. To demonstrate the utility of the newly developed adjoint model, we conduct simulations for two types of atmospheric CO 2 observations, namely the tower-based in situ CO 2 mixing ratio and satellite-derived column-averaged CO 2 mixing ratio (X CO 2 ). A comparison between the sensitivity to surface flux calculated by the MPAS-CO 2 adjoint model with its counterpart from CarbonTracker–Lagrange (CT-L) reveals a spatial agreement but notable magnitude differences. These differences, particularly evident for X CO 2 , might be attributed to the two model systems' differences in the simulation configuration, spatial resolution, and treatment of vertical mixing processes. Moreover, this comparison highlights the substantial loss of information in the atmospheric CO 2 observations due to CT-L's spatial domain limitation. Furthermore, the adjoint sensitivity analysis demonstrates that the sensitivities to both surface flux and initial CO 2 conditions spread out throughout the entire Northern Hemisphere within a month. MPAS-CO 2 forward, TL, and adjoint models stand out for their calculation efficiency and variable-resolution capability, making them competitive in computational cost. In conclusion, the successful development of the MPAS-CO 2 TL and adjoint models, and their integration into the MPAS-CO 2 system, establish the possibility of using MPAS's unique features in atmospheric CO 2 transport sensitivity studies and in inverse modeling with advanced methods such as variational data assimilation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Materials Data on Tl(CoSe)2 by Materials Project

TlCo2Se2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Co+1.50+ is bonded to four equivalent Se2- atoms to form a mixture of corner and edge-sharing CoSe4 tetrahedra. All Co–Se bond lengths are 2.34 Å. Tl1+ is bonded in a body-centered cubic geometry to eight equivalent Se2- atoms. All Tl–Se bond lengths are 3.44 Å. Se2- is bonded in a 4-coordinate geometry to four equivalent Co+1.50+ and four equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl(CoS)2 by Materials Project

TlCo2S2 is alpha bismuth trifluoride-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Co+1.50+ is bonded to four equivalent S2- atoms to form a mixture of edge and corner-sharing CoS4 tetrahedra. All Co–S bond lengths are 2.21 Å. Tl1+ is bonded in a body-centered cubic geometry to eight equivalent S2- atoms. All Tl–S bond lengths are 3.37 Å. S2- is bonded in a 4-coordinate geometry to four equivalent Co+1.50+ and four equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

First-Principles Calculations of the Structural, Electronic, Optical, and Mechanical Properties of 21 Pyrophosphate Crystals

Pyrophosphate crystals have a wide array of applications in industrial and biomedical fields. However, fundamental understanding of their electronic structure, optical, and mechanical properties is still scattered and incomplete. In the present research, we report a comprehensive theoretical investigation of 21 pyrophosphates A 2 M (H 2 P 2 O 7 ) 2 •2H 2 O with either triclinic or orthorhombic crystal structure. The molecule H 2 P 2 O 7 is the dominant molecular unit, whereas A = (K, Rb, NH 4 , Tl), M = (Zn, Cu, Mg, Ni, Co, Mn), and H 2 O stand for the cation elements, transition metals, and the water molecules, respectively. The electronic structure, interatomic bonding, partial charge distribution, optical properties, and mechanical properties are investigated by first-principles calculations based on density functional theory (DFT). Most of these 21 crystals are theoretically investigated for the first time. The calculated results show a complex interplay between A, M, H 2 P 2 O 7 , and H 2 O, resulting in either metallic, half-metallic, or semi-conducting characteristics. The novel concept of total bond order density (TBOD) is used as a single quantum mechanical metric to characterize the internal cohesion of these crystals to correlate with the calculated properties, especially the mechanical properties. This work provides a large database for pyrophosphate crystals and a road map for potential applications of a wider variety of phosphates.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl2CoF4 by Materials Project

Tl2CoF4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Co2+ is bonded to six F1- atoms to form corner-sharing CoF6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.01 Å) and four longer (2.09 Å) Co–F bond lengths. Tl1+ is bonded in a 9-coordinate geometry to nine F1- atoms. There are five shorter (2.94 Å) and four longer (2.96 Å) Tl–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted linear geometry to two equivalent Co2+ and four equivalent Tl1+ atoms. In the second F1- site, F1- is bonded to one Co2+ and five equivalent Tl1+ atoms to form a mixture of distorted edge and corner-sharing FTl5Co octahedra. The corner-sharing octahedra tilt angles range from 0–2°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Be2Tl2Co(O3F4)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlPt3O4 by Materials Project

TlTl(Pt3O4)2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of four thallium molecules and one Tl(Pt3O4)2 framework. In the Tl(Pt3O4)2 framework, Pt+2.33+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Pt–O bond lengths are 2.05 Å. Tl1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Tl–O bond lengths are 2.42 Å. O2- is bonded to three equivalent Pt+2.33+ and one Tl1+ atom to form a mixture of distorted edge and corner-sharing OTlPt3 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl2CoH12(SO7)2 by Materials Project

CoTl2H12(SO7)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Co2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.05–2.17 Å. Tl1+ is bonded in a 6-coordinate geometry to eight O2- atoms. There are a spread of Tl–O bond distances ranging from 2.83–3.47 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the sixth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. S6+ is bonded in a tetrahedral geometry to four O2- atoms. There is two shorter (1.49 Å) and two longer (1.50 Å) S–O bond length. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Tl1+ and one S6+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Co2+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Tl1+ and one S6+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Tl1+ and one S6+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Tl1+ and one S6+ atom. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Co2+, one Tl1+, and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Co2+, one Tl1+, and two H1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl2CoH12(SeO7)2 by Materials Project

CoTl2H12(SeO7)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Co2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Co–O bond distances ranging from 2.07–2.15 Å. Tl1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Tl–O bond distances ranging from 2.82–3.36 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (0.99 Å) and one longer (1.75 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.70 Å) H–O bond length. Se6+ is bonded in a tetrahedral geometry to four O2- atoms. There are a spread of Se–O bond distances ranging from 1.67–1.69 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Tl1+, one H1+, and one Se6+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one Co2+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Tl1+ and one Se6+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Tl1+, one H1+, and one Se6+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Tl1+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one Co2+, one Tl1+, and two H1+ atoms. In the seventh O2- site, O2- is bonded in a distorted water-like geometry to one Co2+, one Tl1+, and two H1+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1972

Chemical fractionations in meteorites. V - Volatile and siderophile elements in achondrites and ocean ridge basalts.

Eighteen achondrites and 4 terrestrial basalts (3 ocean ridge, 1 continental) were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Co, Cs, Cu, Ga, In, Ir, Rb, Se, Tl and Zn. Samples included 7 eucrites, 5 howardites, 2 nakhlites, 2 shergottites, an angrite, and an aubrite. Light and dark portions of the gas-rich meteorites Kapoeta and Pesyanoe were analyzed separately. Nakhlites and shergottites have volatile element abundances similar to those in ocean ridge basalts; eucrites, howardites, and angrites show greater depletions by an order of magnitude and less similar abundance patterns. In terms of a two-component model of planetary accretion, the parent planets contained the following percentages of low-temperature material: eucrites 0.8, nakhlites 38, shergottites 28. Shergottites may be genetically related to L-chondrites. The siderophile element pattern of achondrites resembles that of the moon, but with less extreme depletions.

Laul, J. C.↗
DOE OSTI2020

Materials Data on TlCoCl3 by Materials Project

TlCoCl3 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are two inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to six equivalent Cl1- atoms to form CoCl6 octahedra that share corners with six equivalent TlCl12 cuboctahedra, faces with six equivalent TlCl12 cuboctahedra, and faces with two equivalent CoCl6 octahedra. There are three shorter (2.42 Å) and three longer (2.43 Å) Co–Cl bond lengths. In the second Co2+ site, Co2+ is bonded to six equivalent Cl1- atoms to form CoCl6 octahedra that share corners with six equivalent TlCl12 cuboctahedra, faces with six equivalent TlCl12 cuboctahedra, and faces with two equivalent CoCl6 octahedra. There are three shorter (2.42 Å) and three longer (2.43 Å) Co–Cl bond lengths. Tl1+ is bonded to twelve Cl1- atoms to form distorted TlCl12 cuboctahedra that share corners with six equivalent TlCl12 cuboctahedra, corners with six CoCl6 octahedra, faces with eight equivalent TlCl12 cuboctahedra, and faces with six CoCl6 octahedra. The corner-sharing octahedra tilt angles range from 14–19°. There are a spread of Tl–Cl bond distances ranging from 3.45–3.82 Å. There are two inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Co2+ and four equivalent Tl1+ atoms. In the second Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Co2+ and four equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl(CoSb3)16 by Materials Project

Tl(CoSb3)16 is Skutterudite-derived structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are five inequivalent Co2+ sites. In the first Co2+ site, Co2+ is bonded to six Sb+0.69- atoms to form CoSb6 octahedra that share corners with six CoSb6 octahedra and a faceface with one TlSb12 cuboctahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are a spread of Co–Sb bond distances ranging from 2.53–2.55 Å. In the second Co2+ site, Co2+ is bonded to six Sb+0.69- atoms to form corner-sharing CoSb6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are one shorter (2.53 Å) and five longer (2.54 Å) Co–Sb bond lengths. In the third Co2+ site, Co2+ is bonded to six Sb+0.69- atoms to form corner-sharing CoSb6 octahedra. The corner-sharing octahedra tilt angles range from 51–53°. There are two shorter (2.53 Å) and four longer (2.54 Å) Co–Sb bond lengths. In the fourth Co2+ site, Co2+ is bonded to six Sb+0.69- atoms to form corner-sharing CoSb6 octahedra. The corner-sharing octahedral tilt angles are 52°. All Co–Sb bond lengths are 2.54 Å. In the fifth Co2+ site, Co2+ is bonded to six Sb+0.69- atoms to form CoSb6 octahedra that share corners with six CoSb6 octahedra and faces with two equivalent TlSb12 cuboctahedra. The corner-sharing octahedra tilt angles range from 52–53°. There are two shorter (2.54 Å) and four longer (2.55 Å) Co–Sb bond lengths. Tl1+ is bonded to twelve Sb+0.69- atoms to form TlSb12 cuboctahedra that share faces with eight CoSb6 octahedra. There are four shorter (3.40 Å) and eight longer (3.41 Å) Tl–Sb bond lengths. There are sixteen inequivalent Sb+0.69- sites. In the first Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ atoms. In the second Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ atoms. In the third Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ atoms. In the fourth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ and one Tl1+ atom. In the fifth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ and one Tl1+ atom. In the sixth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ atoms. In the seventh Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ atoms. In the eighth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two Co2+ atoms. In the ninth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ atoms. In the tenth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ atoms. In the eleventh Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ atoms. In the twelfth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ and one Tl1+ atom. In the thirteenth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ atoms. In the fourteenth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ atoms. In the fifteenth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ atoms. In the sixteenth Sb+0.69- site, Sb+0.69- is bonded in a 2-coordinate geometry to two equivalent Co2+ and one Tl1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TlCoCl3 by Materials Project

TlCoCl3 crystallizes in the orthorhombic Pbca space group. The structure is three-dimensional. Co2+ is bonded to six Cl1- atoms to form CoCl6 octahedra that share corners with six equivalent TlCl12 cuboctahedra, faces with six equivalent TlCl12 cuboctahedra, and faces with two equivalent CoCl6 octahedra. There are a spread of Co–Cl bond distances ranging from 2.41–2.44 Å. Tl1+ is bonded to twelve Cl1- atoms to form distorted TlCl12 cuboctahedra that share corners with six equivalent TlCl12 cuboctahedra, corners with six equivalent CoCl6 octahedra, faces with eight equivalent TlCl12 cuboctahedra, and faces with six equivalent CoCl6 octahedra. The corner-sharing octahedra tilt angles range from 13–20°. There are a spread of Tl–Cl bond distances ranging from 3.41–3.87 Å. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Co2+ and four equivalent Tl1+ atoms. In the second Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Co2+ and four equivalent Tl1+ atoms. In the third Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two equivalent Co2+ and four equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Spin‐Orbit Effects in a Thallium Borohydride Stabilized by Coordination to Bis(diisopropylamino)Cyclopropenylidene (BAC)

The reaction of Tl(OTf) with 2 equiv of bis(diisopropylamino)cyclopropenylidene (BAC) in THF results in formation of [Tl(BAC) 2 (OTf)] (1) in moderate yields. Subsequent reaction of 1 with [K][H 2 -9-BBN] ([H 2 -9-BBN] − = dihydrido 9-boratabicyclo[3.3.1]nonane) in THF results in formation of [Tl(BAC)(μ-H 2 -9-BBN)] 2 (3), also in moderate yield. Complex 3 is the first reported thallium borohydride. We attribute its thermal stability to the strong donor ability of the BAC co-ligand. Both 1 and 3 exhibit trigonal pyramidal geometries about Tl + in the solid-state, indicative of the presence of stereochemically active lone pairs. The hydride environment in 3 is calculated to exhibit a 3.9 ppm downfield shift attributed to spin-orbit effects from the adjacent Tl center.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on Tl(CuO)2 by Materials Project

Tl(CuO)2 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Cu–O bond lengths are 1.98 Å. In the second Cu+1.50+ site, Cu+1.50+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.83 Å. Tl1+ is bonded in an L-shaped geometry to two equivalent O2- atoms. Both Tl–O bond lengths are 2.48 Å. O2- is bonded in a 4-coordinate geometry to three Cu+1.50+ and one Tl1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl2Co2(SO4)3 by Materials Project

Co2Tl2(SO4)3 crystallizes in the cubic P2_13 space group. The structure is three-dimensional. there are two inequivalent Co4+ sites. In the first Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent SO4 tetrahedra. There are three shorter (2.10 Å) and three longer (2.12 Å) Co–O bond lengths. In the second Co4+ site, Co4+ is bonded to six O2- atoms to form CoO6 octahedra that share corners with six equivalent SO4 tetrahedra. There are three shorter (2.11 Å) and three longer (2.15 Å) Co–O bond lengths. There are two inequivalent Tl3+ sites. In the first Tl3+ site, Tl3+ is bonded in a 3-coordinate geometry to three equivalent O2- atoms. All Tl–O bond lengths are 2.90 Å. In the second Tl3+ site, Tl3+ is bonded in a 3-coordinate geometry to three equivalent O2- atoms. All Tl–O bond lengths are 2.94 Å. S+3.33+ is bonded to four O2- atoms to form SO4 tetrahedra that share corners with four CoO6 octahedra. The corner-sharing octahedra tilt angles range from 14–49°. There are a spread of S–O bond distances ranging from 1.48–1.50 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Co4+, one Tl3+, and one S+3.33+ atom. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Co4+ and one S+3.33+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to one Co4+ and one S+3.33+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Co4+, one Tl3+, and one S+3.33+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Transfer Learning Meets Embedded Correlated Wavefunction Theory for Chemically Accurate Molecular Simulations: Application to Calcium Carbonate Ion Pairing

Achieving chemical accuracy for molecular simulations remains a central challenge in computational chemistry. Here, we present an embedded correlated wavefunction transfer learning (ECW-TL) framework for accurately simulating molecular dynamics in the condensed phase. ECW-TL incorporates high-level electron exchange and correlation effects in ECW theory while preserving the training and computational efficiency of machine-learned interatomic potentials. We demonstrate the framework on Ca 2+ –CO 3 2– ion pairing in aqueous solution, a key process underlying CO 2 mineralization in seawater. As proof of principle, we first show that fine-tuning a DFT-revPBE-D3(BJ) baseline model with embedded-DFT-SCAN data reproduces the DFT-SCAN free-energy surface within 1 kcal/mol across all solvation states. Extending the framework to embedded MP2 and localized natural-orbital CCSD(T) further refines the free-energy profile, revealing the crucial role of exact electron exchange and correlation in determining ion-pair stability and structure. The computed ion-pair association free energy is in quantitative agreement with experimental measurements, further validating the accuracy of the ECW-TL framework. ECW-TL thus provides a general, data-efficient route for transferring CW accuracy to efficient simulations of complex aqueous and interfacial chemical processes.

cluster chemistry↗