scholarly journals Interplay of high-precision shock wave experiments with first-principles theory to explore molecular systems at extreme conditions: A perspective

2021 ◽  
Vol 129 (21) ◽  
pp. 210904
Author(s):  
M. D. Knudson ◽  
M. P. Desjarlais
Keyword(s):  
Shock Wave ◽  
High Precision ◽  
First Principles ◽  
Extreme Conditions ◽  
Molecular Systems

Development of the ChIMES Force Field for Reactive Molecular Systems: Carbon Monoxide at Extreme Conditions

2019 ◽  
Author(s):  
Rebecca Lindsey ◽  
Nir Goldman ◽  
Laurence E. Fried ◽  
Sorin Bastea
Keyword(s):  
Carbon Monoxide ◽  
Molecular System ◽  
Interaction Model ◽  
System Size ◽  
Single Atom ◽  
Reactive System ◽  
Extreme Conditions ◽  
Ambient Conditions ◽  
Molecular Systems ◽  
Three Body

<p>The interatomic Chebyshev Interaction Model for Efficient Simulation (ChIMES) is based on linear combinations of Chebyshev polynomials describing explicit two- and three-body interactions. Recently, the ChIMES model has been developed and applied to a molten metallic system of a single atom type (carbon), as well as a non-reactive molecular system of two atom types at ambient conditions (water). Here, we continue application of ChIMES to increasingly complex problems through extension to a reactive system. Specifically, we develop a ChIMES model for carbon monoxide under extreme conditions, with built-in transferability to nearby state points. We demonstrate that the resulting model recovers much of the accuracy of DFT while exhibiting a 10<sup>4</sup>increase in efficiency, linear system size scalability and the ability to overcome the significant system size effects exhibited by DFT.</p>

scholarly journals Computational Methods for Ab Initio Molecular Dynamics

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Eric Paquet ◽  
Herna L. Viktor
Keyword(s):  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
Ab Initio ◽  
First Principles ◽  
Density Functional ◽  
Path Integrals ◽  
Ab Initio Molecular Dynamics ◽  
Molecular Systems ◽  
Hartree Fock ◽  
Computational Perspective

Ab initio molecular dynamics is an irreplaceable technique for the realistic simulation of complex molecular systems and processes from first principles. This paper proposes a comprehensive and self-contained review of ab initio molecular dynamics from a computational perspective and from first principles. Quantum mechanics is presented from a molecular dynamics perspective. Various approximations and formulations are proposed, including the Ehrenfest, Born–Oppenheimer, and Hartree–Fock molecular dynamics. Subsequently, the Kohn–Sham formulation of molecular dynamics is introduced as well as the afferent concept of density functional. As a result, Car–Parrinello molecular dynamics is discussed, together with its extension to isothermal and isobaric processes. Car–Parrinello molecular dynamics is then reformulated in terms of path integrals. Finally, some implementation issues are analysed, namely, the pseudopotential, the orbital functional basis, and hybrid molecular dynamics.

Rotational–vibrational resonance states

2020 ◽  
Vol 22 (27) ◽  
pp. 15081-15104 ◽  
Author(s):  
Attila G. Császár ◽  
Irén Simkó ◽  
Tamás Szidarovszky ◽  
Gerrit C. Groenenboom ◽  
Tijs Karman ◽  
...  
Keyword(s):  
First Principles ◽  
Quantum Chemical ◽  
Vibrational Resonance ◽  
Resonance States ◽  
Molecular Systems ◽  
Chemical Techniques

All molecular systems possess a significant number of rovibrational resonance states accessible via spectroscopic and scattering experiments, which can also be computed and rationalized by a variety of first-principles quantum-chemical techniques.

Identifying the structure of 4-chlorophenyl isocyanide adsorbed on Au(111) and Pt(111) surfaces by first-principles simulations of Raman spectra

2017 ◽  
Vol 19 (48) ◽  
pp. 32389-32397 ◽  
Author(s):  
Wei Hu ◽  
Sai Duan ◽  
Yujin Zhang ◽  
Hao Ren ◽  
Jun Jiang ◽  
...  
Keyword(s):  
Raman Spectra ◽  
High Precision ◽  
First Principles ◽  
Simulation Method ◽  
Hollow Site

A high-precision Raman simulation method is developed. Using this method, we reveal that 4-chlorophenyl isocyanide prefers to adsorb on the top site of Au(111) with a vertical configuration, but with a bent configuration on the hollow site of Pt(111).

NUCLEOSYNTHESIS IN SUPERNOVA SHOCK WAVES

1967 ◽  
Vol 45 (7) ◽  
pp. 2315-2332 ◽  
Author(s):  
J. W. Truran ◽  
W. D. Arnett ◽  
A. G. W. Cameron
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Neutron Flux ◽  
Neutron Capture ◽  
Alpha Particles ◽  
Extreme Conditions ◽  
Stellar Envelope ◽  
Capture Process ◽  
Thermonuclear Reactions ◽  
Supernova Explosions

It is generally assumed that element synthesis will take place readily under the extreme conditions believed to exist in supernova explosions. We have examined the types of thermonuclear reactions that can occur in a supernova shock wave which propagates through the stellar envelope, in which a temperature ~5 × 109 °K may occur for ~10−2 seconds. The calculations are performed using a network of nuclei connected to their neighbors by absorption or emission of neutrons, protons, alpha particles and photons (Truran et al. 1966). The results show that iron-peak elements can be produced by a supernova shock wave, but the iron-peak composition observed in nature is not produced unless some transformation of protons to neutrons has taken place in the material before the passage of the shock wave. Furthermore, a neutron flux sufficient to drive the rapid neutron-capture process is not attained under these conditions in the stellar envelope.

A First-Principles Study of Phase Transition of Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine (HMX) under Static Compression

2016 ◽  
Vol 258 ◽  
pp. 33-36
Author(s):  
Lei Zhang ◽  
Sheng Li Jiang ◽  
Jun Chen
Keyword(s):  
Phase Transition ◽  
First Principles ◽  
Condensed Matter ◽  
Interaction Energies ◽  
Static Compression ◽  
Molecular Systems ◽  
Β Phase ◽  
Equation Of States ◽  
Structure Of Molecules ◽  
Δ Phase

The issue of HMX phase transition under hydrostatic compression is not clear and experiments show conflicting results. Effective solution via first-principles simulation is challenged by difficulty of accurate prediction of Van der Waals interaction, which exists ubiquitously and is crucial for determining the structure of molecules and condensed matter. We have contributed to this by constructing a set of pseudopotentials and pseudoatomic orbital basis, specialized for molecular systems with C/H/N/O elements. The reliability of the method is verified from the interaction energies of 45 complexes (comparing to the results of coupled cluster with singles and doubles (Triple) (CCSD)(T)) and the crystalline structures of 7 typical explosives (comparing to experiments). Using this method, we complete the phase diagram of HMX under static compression up to 50 GPa. We make it clear that no β→δ/ε→δ phase transition occurs at 27 GPa, which has long been a hot debate in experiments. A possible γ→β phase transition is found at around 2.10 GPa in the environment of vapour. We have also predicted the equation of states for α-, δ-, and γ-HMX, which are experimentally absent.

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