scholarly journals Assessment of DFT Approaches in Noble Gas Clathrate-like Clusters: Stability and Thermodynamics

2021 ◽  
Author(s):  
Raquel Yanes-Rodríguez ◽  
Rita Prosmiti
Keyword(s):  
Electronic Structure ◽  
Density Functional ◽  
Noble Gas ◽  
Natural Orbital ◽  
Electronic Structure Methods ◽  
Local Pair

We have assessed the performance and accuracy of different wavefunction-based electronic structure methods, such as DFMP2 and domain-based local pair-natural orbital (DLPNO-CCSD(T)), as well as a variety of density functional...

scholarly journals Assessing Conformer Energies using Electronic Structure and Machine Learning Methods

2020 ◽  
Author(s):  
Dakota Folmsbee ◽  
Geoffrey Hutchison
Keyword(s):  
Machine Learning ◽  
Electronic Structure ◽  
Density Functional ◽  
Large Scale ◽  
Single Point ◽  
Semiempirical Method ◽  
Coupled Cluster ◽  
Scale Evaluation ◽  
Machine Learning Methods ◽  
Electronic Structure Methods

We have performed a large-scale evaluation of current computational methods, including conventional small-molecule force fields, semiempirical, density functional, ab initio electronic structure methods, and current machine learning (ML) techniques to evaluate relative single-point energies. Using up to 10 local minima geometries across ~700 molecules, each optimized by B3LYP-D3BJ with single-point DLPNO-CCSD(T) triple-zeta energies, we consider over 6,500 single points to compare the correlation between different methods for both relative energies and ordered rankings of minima. We find promise from current ML methods and recommend methods at each tier of the accuracy-time tradeoff, particularly the recent GFN2 semiempirical method, the B97-3c density functional approximation, and RI-MP2 for accurate conformer energies. The ANI family of ML methods shows promise, particularly the ANI-1ccx variant trained in part on coupled-cluster energies. Multiple methods suggest continued improvements should be expected in both performance and accuracy.

scholarly journals Assessing Conformer Energies using Electronic Structure and Machine Learning Methods

2020 ◽  
Author(s):  
Dakota Folmsbee ◽  
Geoffrey Hutchison
Keyword(s):  
Machine Learning ◽  
Electronic Structure ◽  
Density Functional ◽  
Large Scale ◽  
Single Point ◽  
Semiempirical Method ◽  
Coupled Cluster ◽  
Scale Evaluation ◽  
Machine Learning Methods ◽  
Electronic Structure Methods

We have performed a large-scale evaluation of current computational methods, including conventional small-molecule force fields, semiempirical, density functional, ab initio electronic structure methods, and current machine learning (ML) techniques to evaluate relative single-point energies. Using up to 10 local minima geometries across ~700 molecules, each optimized by B3LYP-D3BJ with single-point DLPNO-CCSD(T) triple-zeta energies, we consider over 6,500 single points to compare the correlation between different methods for both relative energies and ordered rankings of minima. We find promise from current ML methods and recommend methods at each tier of the accuracy-time tradeoff, particularly the recent GFN2 semiempirical method, the B97-3c density functional approximation, and RI-MP2 for accurate conformer energies. The ANI family of ML methods shows promise, particularly the ANI-1ccx variant trained in part on coupled-cluster energies. Multiple methods suggest continued improvements should be expected in both performance and accuracy.

scholarly journals A look at the density functional theory zoo with the advanced GMTKN55 database for general main group thermochemistry, kinetics and noncovalent interactions

2017 ◽  
Vol 19 (48) ◽  
pp. 32184-32215 ◽  
Author(s):  
Lars Goerigk ◽  
Andreas Hansen ◽  
Christoph Bauer ◽  
Stephan Ehrlich ◽  
Asim Najibi ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Noncovalent Interactions ◽  
Main Group ◽  
Density Functionals ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Benchmark Database ◽  
Electronic Structure Methods

We present the updated and extended GMTKN55 benchmark database for more accurate and extensive energetic evaluation of density functionals and other electronic structure methods with detailed guidelines for method users.

scholarly journals Relativistic Effects on the Equation-of-State of the Light Actinides

2005 ◽  
Vol 893 ◽  
Author(s):  
Alexander Landa ◽  
Per Söderlind
Keyword(s):  
Electronic Structure ◽  
Equation Of State ◽  
Density Functional ◽  
Relativistic Effects ◽  
Model Systems ◽  
Face Centered Cubic ◽  
Electronic Structure Methods ◽  
The Face ◽  
Face Centered ◽  
Structure Calculations

AbstractThe effect of the relativistic spin-orbit (SO)interaction on the bonding in the early actinides has been investigated by means of electronic-structure calculations. Specifically, the equation of state (EOS) for the face-centered cubic (fcc) model systems of these metals has been calculated from the first-principles density-functional (DFT) theory. Traditionally, the SO interaction in electronic-structure methods is implemented as a perturbation to the Hamiltonian that is solved for basis functions that explicitly do not depend on SO coupling. Here this approximation is shown to compare well with the fully relativistic Dirac treatment. It is further shown that SO coupling has a gradually increasing effect on the EOS as one proceeds through the actinides and the effect is diminished as density increases.

scholarly journals Introduction to first-principles electronic structure methods: Application to actinide materials

2006 ◽  
Vol 21 (12) ◽  
pp. 2979-2985 ◽  
Author(s):  
John E. Klepeis
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Background Information ◽  
Quantum Molecular Dynamics ◽  
Generalized Gradient ◽  
Sufficient Detail ◽  
Current Controversy ◽  
Electronic Structure Methods

This paper provides an introduction for non-experts to first-principles electronic structure methods that are widely used in condensed-matter physics. Particular emphasis is placed on giving the appropriate background information needed to better appreciate the use of these methods to study actinide and other materials. Specifically, the underlying theory is described in sufficient detail to enable an understanding of the relative strengths and weaknesses of the methods. In addition, the meaning of commonly used terminology is explained, including density functional theory (DFT), local density approximation (LDA), and generalized gradient approximation (GGA), as well as linear muffin-tin orbital (LMTO), linear augmented plane wave (LAPW), and pseudopotential methods. Methodologies that extend the basic theory to address specific limitations are also briefly discussed. Finally, a few illustrative applications are presented, including quantum molecular dynamics (QMD) simulations and studies of surfaces, impurities, and defects. The paper concludes by addressing the current controversy regarding magnetic calculations for actinide materials.

scholarly journals Introduction to First-Principles Electronic Structure Methods: Application to Actinide Materials

2005 ◽  
Vol 893 ◽  
Author(s):  
John E Klepeis
Keyword(s):  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Condensed Matter ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Current Controversy ◽  
Electronic Structure Methods

AbstractThe purpose of this paper is to provide an introduction for non-experts to first-principles electronic structure methods that are widely used in the field of condensed-matter physics, including applications to actinide materials. The methods I describe are based on density functional theory (DFT) within the local density approximation (LDA) and the generalized gradient approximation (GGA). In addition to explaining the meaning of this terminology I also describe the underlying theory itself in some detail in order to enable a better understanding of the relative strengths and weaknesses of the methods. I briefly mention some particular numerical implementations of DFT, including the linear muffin-tin orbital (LMTO), linear augmented plane wave (LAPW), and pseudopotential methods, as well as general methodologies that go beyond DFT and specifically address some of the weaknesses of the theory. The last third of the paper is devoted to a few selected applications that illustrate the ideas discussed in the first two-thirds. In particular, I conclude by addressing the current controversy regarding magnetic DFT calculations for actinide materials. Throughout this paper particular emphasis is placed on providing the appropriate background to enable the non-expert to gain a better appreciation of the application of first-principles electronic structure methods to the study of actinide and other materials.

Assessment of electronic structure methods for the determination of the ground spin states of Fe(ii), Fe(iii) and Fe(iv) complexes

2017 ◽  
Vol 19 (20) ◽  
pp. 13049-13069 ◽  
Author(s):  
Pragya Verma ◽  
Zoltan Varga ◽  
Johannes E. M. N. Klein ◽  
Christopher J. Cramer ◽  
Lawrence Que ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Spin States ◽  
Functional Theory ◽  
Electronic Structure Methods

We studied spin states of Fe2+ ion, gaseous FeO, and 14 Fe(ii), Fe(iii) and Fe(iv) complexes using density functional theory.

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