Spin-cluster expansion: Parametrization of the general adiabatic magnetic energy surface withab initioaccuracy

2004 ◽  
Vol 69 (10) ◽  
Author(s):  
R. Drautz ◽  
M. Fähnle
Keyword(s):  
Cluster Expansion ◽  
Energy Surface ◽  
Magnetic Energy ◽  
Spin Cluster

scholarly journals Linear Atomic Cluster Expansion Force Fields for Organic Molecules: beyond RMSE

2021 ◽  
Author(s):  
David Peter Kovacs ◽  
Cas van der Oord ◽  
Jiri Kucera ◽  
Alice Allen ◽  
Daniel Cole ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Cluster Expansion ◽  
Organic Molecules ◽  
Energy Surface ◽  
Force Fields ◽  
Atomic Cluster ◽  
Symmetric Polynomials ◽  
Benchmark Datasets ◽  
Expansion Force

We demonstrate that fast and accurate linear force fields can be built for molecules using the Atomic Cluster Expansion (ACE) framework. The ACE models parametrize the Potential Energy Surface in terms of body ordered symmetric polynomials making the functional form reminiscent of traditional molecular mechanics force fields. We show that the 4 or 5-body ACE force fields improve on the accuracy of the empirical force fields by up to a factor of 10, reaching the accuracy typical of recently proposed machine learning based approaches. We not only show state of the art accuracy and speed on the widely used MD17 and ISO17 benchmark datasets, but also go beyond RMSE by comparing a number of ML and empirical force fields to ACE on more important tasks such as normal mode prediction, high temperature molecular dynamics, dihedral torsional profile prediction and even bond breaking. We also demonstrate the smoothness, transferability and extrapolation capabilities of ACE on a new challenging benchmark dataset comprising a potential energy surface of a flexible drug-like molecule.

scholarly journals Atomistic spin model based on a spin-cluster expansion technique: Application to the IrMn3/Co interface

2011 ◽  
Vol 83 (2) ◽  
Author(s):  
L. Szunyogh ◽  
L. Udvardi ◽  
J. Jackson ◽  
U. Nowak ◽  
R. Chantrell
Keyword(s):  
Cluster Expansion ◽  
Spin Model ◽  
Spin Cluster ◽  
Model Based ◽  
Expansion Technique

The magnetic energy surface of cobalt precipitates in copper determined by time-resolved neutron depolarization

1988 ◽  
Vol 58 (6) ◽  
pp. 573-592
Author(s):  
A. Veider ◽  
G. Badurek ◽  
H. Weinfurter ◽  
K. Stierstadt
Keyword(s):  
Energy Surface ◽  
Magnetic Energy ◽  
Time Resolved ◽  
Neutron Depolarization

Trial production of γ-type energy filtering TEM

1995 ◽  
Vol 53 ◽  
pp. 604-605
Author(s):  
Y. Taniguchi ◽  
E. Nakazawa ◽  
S. Taya
Keyword(s):  
Magnetic Energy ◽  
Electron Optics ◽  
Electron Microscopic ◽  
Mass Spectrometers ◽  
Ion Optics ◽  
Energy Filtering ◽  
New Information ◽  
New Type ◽  
Fringing Fields

Imaging energy filters can add new information to electron microscopic images with respect to energy-axis, so-called electron spectroscopic imaging (ESI). Recently, many good results have been reported using this imaging technique. ESI also allows high-contrast observation of unstained biological samples, becoming a trend of the field of morphology. We manufactured a new type of energy filter as a trial production. This energy filter consists of two magnets, and we call γ-filter since the trajectory of electrons shows ‘γ’-shape inside the filter. We evaluated the new energyγ-filter TEM with the γ-filter.Figure 1 shows schematic view of the electron optics of the γ-type energy filter. For the determination of the electron-optics of the γ-type energy filter, we used the TRIO (Third Order Ion Optics) program which has been developed for the design of high resolution mass spectrometers. The TRIO takes the extended fringing fields (EFF) into consideration. EFF makes it difficult to design magnetic energy filters with magnetic sector fields.

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