Sub-microhartree accuracy potential energy surface for H3+ including adiabatic and relativistic effects. II. Rovibrational analysis for H3+ and D3+

1998 ◽  
Vol 108 (7) ◽  
pp. 2837-2846 ◽  
Author(s):  
Ralph Jaquet ◽  
Wojciech Cencek ◽  
Werner Kutzelnigg ◽  
Jacek Rychlewski
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Relativistic Effects

scholarly journals Exploring the potential energy surface of small lead clusters using the gradient embedded genetic algorithm and an adequate treatment of relativistic effects

RSC Advances ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 145-152 ◽  
Author(s):  
Walter A. Rabanal-León ◽  
William Tiznado ◽  
Edison Osorio ◽  
Franklin Ferraro
Keyword(s):  
Genetic Algorithm ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Crucial Role ◽  
Energy Surface ◽  
Relativistic Effects ◽  
Spin Orbit ◽  
Adequate Treatment ◽  
Structural Assignment

Theoretical inclusion of relativistic effects (scalar and spin–orbit) play a crucial role to assure an adequate structural assignment on lead clusters.

Explicitly correlated potential energy surface of , including relativistic and adiabatic corrections

2006 ◽  
Vol 364 (1848) ◽  
pp. 2855-2876 ◽  
Author(s):  
Werner Kutzelnigg ◽  
Ralph Jaquet
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Energy Surface ◽  
Relativistic Effects ◽  
Large Set ◽  
Excited Singlet ◽  
Correct Treatment ◽  
Nuclear Masses ◽  
Explicitly Correlated ◽  
State Potential

After a short historical account of the theory of the ion, two ab initio methods are reviewed that allow the computation of the ground-state potential energy surface (PES) of in the Born–Oppenheimer (BO) approximation, with microhartree or even sub-microhartree accuracy, namely the R12 method and the method of explicitly correlated Gaussians. The BO-PES is improved by the inclusion of relativistic effects and adiabatic corrections. It is discussed how non-adiabatic effects on rotation and vibration can be simulated by corrections to the moving nuclear masses. The importance of the appropriate analytic fit to the computed points of the PES for the subsequent computation of the rovibronic spectrum is addressed. Some recent extensions of the computed PES in the energy region above the barrier to linearity are reviewed. This involves a large set of input geometries and the correct treatment of the dissociation asymptotics, including the coupling with the first excited singlet state. Some comments on this state as well as on the lowest triplet state of are made. The paper ends with a few remarks on the ion .

Active Learning Accelerates Ab Initio Molecular Dynamics on Pericyclic Reactive Energy Surfaces

2020 ◽  
Author(s):  
Shi Jun Ang ◽  
Wujie Wang ◽  
Daniel Schwalbe-Koda ◽  
Simon Axelrod ◽  
Rafael Gomez-Bombarelli
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Transition State ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Computational Cost ◽  
Reactive Trajectories ◽  
Dynamics Simulations ◽  
Energy Surfaces

<div>Modeling dynamical effects in chemical reactions, such as post-transition state bifurcation, requires <i>ab initio</i> molecular dynamics simulations due to the breakdown of simpler static models like transition state theory. However, these simulations tend to be restricted to lower-accuracy electronic structure methods and scarce sampling because of their high computational cost. Here, we report the use of statistical learning to accelerate reactive molecular dynamics simulations by combining high-throughput ab initio calculations, graph-convolution interatomic potentials and active learning. This pipeline was demonstrated on an ambimodal trispericyclic reaction involving 8,8-dicyanoheptafulvene and 6,6-dimethylfulvene. With a dataset size of approximately</div><div>31,000 M062X/def2-SVP quantum mechanical calculations, the computational cost of exploring the reactive potential energy surface was reduced by an order of magnitude. Thousands of virtually costless picosecond-long reactive trajectories suggest that post-transition state bifurcation plays a minor role for the reaction in vacuum. Furthermore, a transfer-learning strategy effectively upgraded the potential energy surface to higher</div><div>levels of theory ((SMD-)M06-2X/def2-TZVPD in vacuum and three other solvents, as well as the more accurate DLPNO-DSD-PBEP86 D3BJ/def2-TZVPD) using about 10% additional calculations for each surface. Since the larger basis set and the dynamic correlation capture intramolecular non-covalent interactions more accurately, they uncover longer lifetimes for the charge-separated intermediate on the more accurate potential energy surfaces. The character of the intermediate switches from entropic to thermodynamic upon including implicit solvation effects, with lifetimes increasing with solvent polarity. Analysis of 2,000 reactive trajectories on the chloroform PES shows a qualitative agreement with the experimentally-reported periselectivity for this reaction. This overall approach is broadly applicable and opens a door to the study of dynamical effects in larger, previously-intractable reactive systems.</div>

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