Constrained nuclear-electronic orbital density functional theory: Energy surfaces with nuclear quantum effects

2020 ◽  
Vol 152 (8) ◽  
pp. 084107 ◽  
Author(s):  
Xi Xu ◽  
Yang Yang
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Quantum Effects ◽  
Functional Theory ◽  
Energy Surfaces ◽  
Nuclear Quantum Effects ◽  
Orbital Density

scholarly journals Molecular dynamics with constrained nuclear electronic orbital density functional theory: Accurate vibrational spectra from efficient incorporation of nuclear quantum effects

2021 ◽  
Author(s):  
Xi Xu ◽  
Zehua Chen ◽  
Yang Yang
Keyword(s):  
Molecular Dynamics ◽  
Density Functional Theory ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Molecular Simulations ◽  
Quantum Effects ◽  
Functional Theory ◽  
Chemical And Biological Systems ◽  
Nuclear Quantum Effects ◽  
Orbital Density

Nuclear quantum effects play a crucial role in many chemical and biological systems involving hydrogen atoms yet are difficult to include in practical molecular simulations. In this Letter, we combine our recently developed methods of constrained nuclear-electronic orbital density functional theory (cNEO-DFT) and constrained minimized energy surface molecular dynamics (CMES-MD) to create a new method for accurately and efficiently describing nuclear quantum effects in molecular simulations. Using this new method, dubbed cNEO-MD, the vibrational spectra of a set of small molecules are calculated and compared with those from conventional ab initio molecular dynamics (AIMD) as well as from experiments. With the same formal scaling, cNEO-MD greatly outperforms AIMD in describing the vibrational modes with significant hydrogen motion characters, demonstrating the promise of cNEO-MD for simulating chemical and biological systems with significant nuclear quantum effects.

scholarly journals The ANI-1ccx and ANI-1x Data Sets, Coupled-Cluster and Density Functional Theory Properties for Molecules

2020 ◽  
Author(s):  
Justin S. Smith ◽  
Roman Zubatyuk ◽  
Benjamin T. Nebgen ◽  
Nicholas Lubbers ◽  
Kipton Barros ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Atomic Charge ◽  
Density Functional Theory Calculations ◽  
Coupled Cluster ◽  
Data Sets ◽  
Data Set ◽  
Functional Theory ◽  
Energy Surfaces

<p>Maximum diversification of data is a central theme in building generalized and accurate machine learning (ML) models. In chemistry, ML has been used to develop models for predicting molecular properties, for example quantum mechanics (QM) calculated potential energy surfaces and atomic charge models. The ANI-1x and ANI-1ccx ML-based eneral-purpose potentials for organic molecules were developed through active learning; an automated data diversification process. Here, we describe the ANI-1x and ANI-1ccx data sets. To demonstrate data set diversity, we visualize them with a dimensionality reduction scheme, and contrast against existing data sets. The ANI-1x data set contains multiple QM properties from 5M density functional theory calculations, while the ANI-1ccx data set contains 500k data points obtained with an accurate CCSD(T)/CBS extrapolation. Approximately 14 million CPU core-hours were expended to generate this data. Multiple QM properties from density functional theory and coupled cluster are provided: energies, atomic forces, multipole moments, atomic charges, and more. We provide this data to the community to aid research and development of ML models for chemistry.</p>

Further developments in the local-orbital density-functional-theory tight-binding method

2001 ◽  
Vol 64 (19) ◽  
Author(s):  
James P. Lewis ◽  
Kurt R. Glaesemann ◽  
Gregory A. Voth ◽  
Jürgen Fritsch ◽  
Alexander A. Demkov ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Tight Binding ◽  
Functional Theory ◽  
Tight Binding Method ◽  
Orbital Density

Theoretical Investigation of the Decarbonylation of Acetaldehyde by Ni+2 Using Density Functional Theory

2013 ◽  
Vol 446-447 ◽  
pp. 168-171
Author(s):  
Hong Fei Liu ◽  
Xin Min Min ◽  
Hai Xia Yang
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Density Functional ◽  
Transition Metal Ions ◽  
Basis Sets ◽  
Functional Theory ◽  
Representative System ◽  
Energy Surfaces ◽  
Ground Potential

The decarbonylation of acetaldehyde assisted by Ni+2, which was selected as a representative system of transition metal ions assisted decarbonylation of acetaldehyde, has been investigated using density functional theory (B3LYP) in conjunction with the 6-31+G** basis sets in C,H,O atoms and Lanl2dz basis sets in Ni atom The geometries and energies of the reactants, intermediates, products and transition states relevant to the reaction were located on the triplet ground potential energy surfaces of [Ni, O, C2,H4]+2. Our calculations indicate the decarbonylation of acetaldehyde takes place through four steps, that is, encounter complexation, CC activation, aldehyde H-shift and nonreactive dissociation, it is that CC activation by Ni+2that lead to the decarbonylation of acetaldehyde.

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