We present an implementation of all-electron density-functional theory for massively parallel GPU-based platforms, using localized atom-centered basis functions and real-space integration grids. ...Special attention is paid to domain decomposition of the problem on non-uniform grids, which enables compute- and memory-parallel execution across thousands of nodes for real-space operations, e.g. the update of the electron density, the integration of the real-space Hamiltonian matrix, and calculation of Pulay forces. To assess the performance of our GPU implementation, we performed benchmarks on three different architectures using a 103-material test set. We find that operations which rely on dense serial linear algebra show dramatic speedups from GPU acceleration: in particular, SCF iterations including force and stress calculations exhibit speedups ranging from 4.5 to 6.6. For the architectures and problem types investigated here, this translates to an expected overall speedup between 3–4 for the entire calculation (including non-GPU accelerated parts), for problems featuring several tens to hundreds of atoms. Additional calculations for a 375-atom Bi2Se3 bilayer show that the present GPU strategy scales for large-scale distributed-parallel simulations.
•Real-space electronic structure theory is naturally suited to GPU acceleration.•Minimal code rewrite was necessary to port domain decomposition algorithms to GPUs.•GPU speedups of 3-4X in overall time-to-solution are observed for the FHI-aims code.•GPU speedups over 10X are observed for algorithms dominated by dense linear algebra.
The biggest research programme within business ethics is arguably Corporate Social Responsibility and all its related streams (Corporate Citizenship, Social Justice, etc.) While there seems to be ...widespread agreement that business ethics is situated between the amoral or even immoral view of Milton Friedman as explicated in his 1970 New York Times paper, and the moral view expounded by R. Edward Freeman, this essay challenges that view. Friedman, maybe owed to his flamboyant writing style and crude and purely rhetorical oversimplifications has been misinterpreted to advocate for managers to be completely amoral maximisers of profitability. This misinterpretation has become common wisdom, despite him clearly stating that the law and the moral standards of surrounding society must limit profit‐seeking behaviour. Freeman's stakeholder theory, on the other hand, is seen as being on the other end of the continuum, arguing for selflessness—another misinterpretation, as I argue with Ed Freeman's help. Instead, I suggest that both Friedman and Freeman represent the virtuous mean of the business ethics continuum and not its extremes because they both base their theories on the idea of the free and socially embedded individual. The two vicious ends of the continuum are inhabited by the unreal, atomised, completely a‐social and selfish individual on the one end, and by the equally unreal collectivised self‐less individual on the other. The mainstream in business ethics has declared the collective and selfless end to be the ideal that must guide practice and research. The selfish and the selfless strawmen have prevented a proper debate in business ethics for too long.
Routine applications of electronic structure theory to molecules and periodic systems need to compute the electron density from given Hamiltonian and, in case of non-orthogonal basis sets, overlap ...matrices. System sizes can range from few to thousands or, in some examples, millions of atoms. Different discretization schemes (basis sets) and different system geometries (finite non-periodic vs. infinite periodic boundary conditions) yield matrices with different structures. The ELectronic Structure Infrastructure (ELSI) project provides an open-source software interface to facilitate the implementation and optimal use of high-performance solver libraries covering cubic scaling eigensolvers, linear scaling density-matrix-based algorithms, and other reduced scaling methods in between. In this paper, we present recent improvements and developments inside ELSI, mainly covering (1) new solvers connected to the interface, (2) matrix layout and communication adapted for parallel calculations of periodic and/or spin-polarized systems, (3) routines for density matrix extrapolation in geometry optimization and molecular dynamics calculations, and (4) general utilities such as parallel matrix I/O and JSON output. The ELSI interface has been integrated into four electronic structure code projects (DFTB+, DGDFT, FHI-aims, SIESTA), allowing us to rigorously benchmark the performance of the solvers on an equal footing. Based on results of a systematic set of large-scale benchmarks performed with Kohn–Sham density-functional theory and density-functional tight-binding theory, we identify factors that strongly affect the efficiency of the solvers, and propose a decision layer that assists with the solver selection process. Finally, we describe a reverse communication interface encoding matrix-free iterative solver strategies that are amenable, e.g., for use with planewave basis sets.
Program title: ELSI Interface
CPC Library link to program files:http://dx.doi.org/10.17632/473mbbznrs.1
Licensing provisions: BSD 3-clause
Programming language: Fortran 2003, with interface to C/C++
External routines/libraries: BLACS, BLAS, BSEPACK (optional), EigenExa (optional), ELPA, FortJSON, LAPACK, libOMM, MPI, MAGMA (optional), MUMPS (optional), NTPoly, ParMETIS (optional), PETSc (optional), PEXSI, PT-SCOTCH (optional), ScaLAPACK, SLEPc (optional), SuperLU_DIST
Nature of problem: Solving the electronic structure from given Hamiltonian and overlap matrices in electronic structure calculations.
Solution method: ELSI provides a unified software interface to facilitate the use of various electronic structure solvers including cubic scaling dense eigensolvers, linear scaling density matrix methods, and other approaches.
In the leadership literature of the past 100 years or so, rhetoric has been a topic for a long time and ethics was introduced some 30 years ago. However, the three topics, leadership, rhetoric, and ...ethics, have not been connected. This is astonishing because when ethical leadership made its comeback, scholars acknowledged the debt that ethical leadership owes to Aristotelian ideas. For Aristotle, leadership, ethics, and rhetoric were inseparable: without ethics, there could neither be good leadership nor rhetoric, and rhetoric was the bridge from leader to follower and back. Aristotle is known as the practical philosopher and we argue that closing this major lacuna in leadership theory, would be beneficial for practice too and would help prevent Theranos‐like scandals. The lacuna lies in what some call a Machiavellian view of leadership and rhetoric: both are regarded as amoral tools to achieve given ends. Aristotle would bristle at that idea. Both, leadership and rhetoric, to be good, must aim at the noble. The noble is not dictated by a heroic despot nor by a selfless saint but is understood by a leader because s/he is a socially embedded individual. We argue that leadership should be understood as personal development, that organisational rules must not inhibit virtue, that leadership is more about listening than talking, that synthesising that which is heard is central, and finally, that the common, not the collective, good is the goal of leadership.
This study offers a fresh approach to the theory and practice of poetry criticism from a narratological perspective. Arguing that lyric poems share basic constituents with narrative fiction, the ...authors utilize the advanced techniques of narratology to invigorate the field of poetic theory and methodology while demonstrating the fruitfulness of this approach by detailed analyses of canonical English poems.
The assessed phase diagram of the boron-carbon system contains a single nonstoichiometric boron-carbide phase of rhombohedral symmetry with a broad, thermodynamically improbable, low temperature ...composition range. We combine first principles total energy calculations with phenomenological thermodynamic modeling to propose a revised low temperature phase diagram that contains
two
boron-carbide phases of differing symmetries and compositions. One structure has composition B
4
C and consists of B
11
C icosahedra and C-B-C chains, with the placement of carbon on the icosahedron breaking rhombohedral symmetry. This phase is destabilized above 600 K by the configurational entropy of alternate carbon substitutions. The other structure, of ideal composition B
13
C
2
, has a broad composition range at high temperature, with rhombohedral symmetry throughout, as observed experimentally.
To solve linear programming problems by interior point methods an approximately centered interior point has to be known. Such a point can be found by an algorithmic approach – a so-called phase 1 ...algorithm or centering algorithm. For random linear programming problems distributed according to the rotation symmetry model, especially with normal distribution, we present probabilistic results on the quality of the origin as starting point and the average number of steps of a centering algorithm.
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