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Possible crystalline modifications of chemical compounds at low temperatures correspond to local minima of the energy landscape. Determining these minima via simulated annealing is one method for the prediction of crystal structures, where…

Materials Science · Physics 2008-10-31 K. Doll , J. C. Schoen , M. Jansen

We propose a novel quantum Monte Carlo method in configuration space, which stochastically samples the contribution from a large secondary space to the effective Hamiltonian in the energy dependent partitioning of L\"owdin. The method…

Chemical Physics · Physics 2015-06-15 Seiichiro Ten-no

The electronic structures of hexagonal beta-Al9Mn3Si and phi-Al10Mn3 are investigated through self-consistent calculations carried out using the LMTO method. This ab-initio approach is combined with an analysis of a simplified hamiltonian…

Materials Science · Physics 2013-10-02 G. Trambly de Laissardiere

Total energies of crystal structures can be calculated to high precision using quantum-based density functional theory (DFT) methods, but the calculations can be time consuming and scale badly with system size. Cluster expansions of total…

Materials Science · Physics 2015-12-31 Qin Gao , Sanxi Yao , Jeff Schneider , Michael Widom

Classical effective potentials are indispensable for any large-scale atomistic simulations, and the relevance of simulation results crucially depends on the quality of the potentials used. For complex alloys like quasicrystals, however,…

Materials Science · Physics 2009-07-07 Peter Brommer , Franz Gähler

A tile Hamiltonian (TH) replaces the actual atomic interactions in a quasicrystal with effective interactions between and within tiles. We studied Al-Co-Cu decagonal quasicrystals described as decorated Hexagon-Boat-Star (HBS) tiles using…

Disordered Systems and Neural Networks · Physics 2007-05-23 Ibrahim Al-Lehyani , Mike Widom

We interpret experimentally known B-Mg-Ru crystals as quasicrystal approximants. These approximant structures imply a deterministic decoration of tiles by atoms that can be extended quasiperiodically. Experimentally observed structural…

Materials Science · Physics 2009-11-10 M. Mihalkovič , M. Widom

Due to their aperiodic nature, quasicrystals are one of the least understood phases in statistical physics. One significant complication they present in comparison to their periodic counterparts is the fact that any quasicrystal can be…

Soft Condensed Matter · Physics 2024-02-01 Etienne Fayen , Laura Filion , Giuseppe Foffi , Frank Smallenburg

We present an efficient \textit{ab initio} method for calculating the electronic structure and total energy of strongly correlated electron systems. The method extends the traditional Gutzwiller approximation for one-particle operators to…

Strongly Correlated Electrons · Physics 2014-07-01 Y. X. Yao , J. Liu , C. Liu , W. C. Lu , C. Z. Wang , K. M. Ho

We have developed an efficient and reliable methodology for crystal structure prediction, merging ab initio total-energy calculations and a specifically devised evolutionary algorithm. This method allows one to predict the most stable…

Materials Science · Physics 2009-11-18 A. R. Oganov , C. W. Glass

We consider a model decagonal quasicrystal of composition Al$_{80.1}$Co$_{19.9}$ -- closely related to actual structures, and using realistic pair potentials -- on a quasilattice of candidate sites. Its ground state, according to…

Materials Science · Physics 2008-09-02 Sejoon Lim , M. Mihalkovic , C. L. Henley

Ab-initio crystal structure prediction depends on accurate calculation of the energies of competing structures. Many DFT codes are available that utilize different approaches to solve the Kohn-Sham equation. We evaluate the consistency of…

Materials Science · Physics 2022-10-20 Vishnu Raghuraman , Yang Wang , Michael Widom

Mechanisms that stabilize quasicrystals are much discussed but not finally resolved. We confirm the random tiling hypothesis and its predictions in a fully atomistic decagonal quasicrystal model by calculating the free energy and the phason…

Materials Science · Physics 2013-05-10 Alexander Kiselev , Michael Engel , Hans-Rainer Trebin

An interatomic potential for Al-Tb alloy around the composition of Al90Tb10 was developed using the deep neural network (DNN) learning method. The atomic configurations and the corresponding total potential energies and forces on each atom…

Materials Science · Physics 2023-07-19 L. Tang , Z. J. Yang , T. Q. Wen , K. M. Ho , M. J. Kramer , C. Z. Wang

The detailed atomic structure of quasicrystals has been an open question for decades. Here, we present a quasilattice-conserved optimization method (quasiOPT), with particular quasiperiodic boundary conditions. As the atomic coordinates…

Materials Science · Physics 2015-06-23 Xiao-Tian Li , Xiao-Bao Yang , Yu-Jun Zhao

We model the quasicrystal-related structure CaCd$_6$, a bcc packing of icosahedral clusters containing tetrahedra which undergo orientational orderings at T<100 K. We use general schemes to evaluate an effective Hamltonian for…

Materials Science · Physics 2012-12-24 Woosong Choi , Christopher L. Henley , Marek Mihalkovic

Icosahedral quasicrystals spontaneously form from the melt in simulations of Al--Cu--Fe alloys. We model the interatomic interactions using oscillating pair potentials tuned to the specific alloy system based on a database of density…

Materials Science · Physics 2020-03-04 Marek Mihalkovic , Michael Widom

We employ a technique that combines the configuration interaction method with the singles-doubles coupled-cluster method to perform calculation of the energy levels, transition amplitudes, lifetimes, g-factors, and magnetic dipole and…

Atomic Physics · Physics 2020-05-08 V. A. Dzuba , V. V. Flambaum , B. M. Roberts

High-energy nuclear collisions have opened a new experimental method to reveal collective behavior in nuclear ground states through the lens of many-body correlations of nucleons. Using ab initio lattice and variational calculations of…

Nuclear Theory · Physics 2025-12-23 Jean-Paul Blaizot , Giuliano Giacalone , Alessandro Lovato

Atomistic simulations provide insights into structure-property relations on an atomic size and length scale, that are complementary to the macroscopic observables that can be obtained from experiments. Quantitative predictions, however, are…

Materials Science · Physics 2021-04-14 Nataliya Lopanitsyna , Chiheb Ben Mahmoud , Michele Ceriotti