Grown from lithium flux, the ErCo5Si3.17silicide is a combination of disordered derivatives of the UCo5Si3and Yb6Co30P19structure types

A ternary hexaerbium triacontacobalt enneakaidecasilicide, ErCo5Si3.17, crystallizes as a combination of disordered variants of the hexagonal UCo5Si3(P63/m) and Yb6Co30P19(P-6) structure types and is closely related to the Sc6Co30Si19and Ce6Rh30Si19types. The Er, Co and three of the Si atoms occupy sites ofm.. symmetry and a fourth Si atom occupies a site of -6.. symmetry. The environment of the Er atom is a 21-vertex pseudo-Frank–Kasper polyhedron. Trigonal prismatic coordination is observed for the Si atoms. The Co atoms are enclosed in heavily deformed cuboctahedra and 11-vertex polyhedra. Crystallochemistry analysis and the data from electronic structure calculations (TB–LMTO–ASA) suggest that the Er atoms form positively charged cations which compensate the negative charge of the [Co12Si9]m−polyanions.

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Crystal and electronic structures of La2LiGe6−x(x= 0.21) and La2LiGe4Si2

Acta Crystallographica Section C Crystal Structure Communications ◽

10.1107/s0108270112031526 ◽

2012 ◽

Vol 68 (8) ◽

pp. i60-i64 ◽

Cited By ~ 4

Author(s):

Andrij Stetskiv ◽

Renata Misztal ◽

Volodymyr Pavlyuk

Keyword(s):

Electronic Structures ◽

Linear Structure ◽

Structure Type ◽

Vertex Polyhedron ◽

Interatomic Distances ◽

Trigonal Prismatic Coordination ◽

A Site ◽

Structure Calculations ◽

Trigonal Prismatic

The synthesis and characterization of a new ternary dilanthanum lithium hexagermanide, La2LiGe6−x(x= 0.21), belonging to the Pr2LiGe6structure type, and a quaternary dilanthanum lithium tetragermanium disilicide, La2LiGe4Si2, which crystallizes as an ordered variant of this type, are reported. In both structures, Li is on a site ofmmmsymmetry. All other atoms are on sites ofm2msymmetry. These structures are new representatives of a homologous linear structure series based on structural fragments of the AlB2, CaF2and ZrSi2structure types. The observed 17-vertex polyhedra are typical for La atoms and the environment of the Li atom is cubic. Two Ge atoms are enclosed in a tetragonal prism with one added atom (nine-vertex polyhedron). The trigonal prismatic coordination is typical for Ge or Si atoms. The metallic nature of the bonding is indicated by the interatomic distances and electronic structure calculations.

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Thulium nickel/lithium distannide, TmNi1−xLixSn2(x= 0.035)

Acta Crystallographica Section E Structure Reports Online ◽

10.1107/s1600536813027335 ◽

2013 ◽

Vol 69 (11) ◽

pp. i76-i76 ◽

Cited By ~ 2

Author(s):

Andrij Stetskiv ◽

Ivan Tarasiuk ◽

Renata Misztal ◽

Volodymyr Pavlyuk

Keyword(s):

Electronic Structure ◽

Three Dimensional ◽

Electronic Structure Calculations ◽

Structure Type ◽

Trigonal Prism ◽

Interatomic Distances ◽

Tricapped Trigonal Prism ◽

Pentagonal Prism ◽

Structure Calculations ◽

Positively Charged

The quaternary thulium nickel/lithium distannide, TmNi1−xLixSn2(x= 0.035), crystallizes in the orthorhombic LuNiSn2structure type. The asymmetric unit contains three Tm sites, six Sn sites, two Ni sites and one Ni/Li site [relative occupancies = 0.895 (8):0.185 (8)]. Site symmetries are .m. for all atoms. The 17-, 18- and 19-vertex distorted pseudo-Frank–Kasper polyhedra are typical for all Tm atoms. Four Sn atoms are enclosed in a 12-vertex deformed cubooctahedron, and another Sn atom is enclosed in a pentagonal prism with three added atoms. A tricapped trigonal prism is typical for a further Sn atom. The coordination number for all Ni atoms and Ni/Li statistical mixtures is 12 (fourcapped trigonal prism [Ni/LiTm5Sn5]). Tm atoms form the base of a prism and Ni/Li atoms are at the centres of the side faces of an [SnTm6Ni/Li3] prism. These isolated prisms are implemented into three-dimensional-nets built out of Sn atoms. Electronic structure calculations using TB-LMTO-ASA suggest that the Tm and Ni/Li atoms form positively chargedn[TmNi/Li]m+polycations which compensate the negative charge of 2n[Sn]m−polyanions. Analysis of the interatomic distances and electronic structure calculations indicate the dominance of a metallic type of bonding.

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Electronic structure calculations of positron lifetimes in nuclear materials: SiC and UO2

SNA + MC 2013 - Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo ◽

10.1051/snamc/201401312 ◽

2014 ◽

Author(s):

Julia Wiktor ◽

Gérald Jomard ◽

Michel Freyss ◽

Marjorie Bertolus

Keyword(s):

Electronic Structure ◽

Electronic Structure Calculations ◽

Nuclear Materials ◽

Positron Lifetimes ◽

Structure Calculations

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Message Passing Neural Networks for Partial Charge Assignment to Metal-Organic Frameworks

10.26434/chemrxiv.12298487 ◽

2020 ◽

Author(s):

Ali Raza ◽

Arni Sturluson ◽

Cory Simon ◽

Xiaoli Fern

Keyword(s):

Electronic Structure ◽

Message Passing ◽

Gas Adsorption ◽

Metal Organic Frameworks ◽

Computational Cost ◽

Electronic Structure Calculations ◽

High Fidelity ◽

Partial Charges ◽

Metal Organic ◽

Structure Calculations

Virtual screenings can accelerate and reduce the cost of discovering metal-organic frameworks (MOFs) for their applications in gas storage, separation, and sensing. In molecular simulations of gas adsorption/diffusion in MOFs, the adsorbate-MOF electrostatic interaction is typically modeled by placing partial point charges on the atoms of the MOF. For the virtual screening of large libraries of MOFs, it is critical to develop computationally inexpensive methods to assign atomic partial charges to MOFs that accurately reproduce the electrostatic potential in their pores. Herein, we design and train a message passing neural network (MPNN) to predict the atomic partial charges on MOFs under a charge neutral constraint. A set of ca. 2,250 MOFs labeled with high-fidelity partial charges, derived from periodic electronic structure calculations, serves as training examples. In an end-to-end manner, from charge-labeled crystal graphs representing MOFs, our MPNN machine-learns features of the local bonding environments of the atoms and learns to predict partial atomic charges from these features. Our trained MPNN assigns high-fidelity partial point charges to MOFs with orders of magnitude lower computational cost than electronic structure calculations. To enhance the accuracy of virtual screenings of large libraries of MOFs for their adsorption-based applications, we make our trained MPNN model and MPNN-charge-assigned computation-ready, experimental MOF structures publicly available.<br>

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