Explicit Consideration of Vibrational Anharmonicity in Molecular Crystals with Quantum-Mechanical Simulations

2020 ◽  
Author(s):  
R. G. Schireman ◽  
M. T. Ruagiero
Keyword(s):  
Molecular Crystals ◽  
Quantum Mechanical ◽  
Vibrational Anharmonicity ◽  
Explicit Consideration

scholarly journals All-Nitrogen Cages and Molecular Crystals: Topological Rules, Stability, and Pyrolysis Paths

Computation ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 91
Author(s):  
Konstantin P. Katin ◽  
Valeriy B. Merinov ◽  
Alexey I. Kochaev ◽  
Savas Kaya ◽  
Mikhail M. Maslov
Keyword(s):  
Room Temperature ◽  
Molecular Crystals ◽  
High Energy ◽  
Binding Energies ◽  
Ab Initio Molecular Dynamics ◽  
Quantum Mechanical ◽  
Intrinsic Reaction Coordinate ◽  
Activation Barriers ◽  
Gibbs Energies ◽  
The Stability

We combined ab initio molecular dynamics with the intrinsic reaction coordinate in order to investigate the mechanisms of stability and pyrolysis of N4 ÷ N120 fullerene-like nitrogen cages. The stability of the cages was evaluated in terms of the activation barriers and the activation Gibbs energies of their thermal-induced breaking. We found that binding energies, bond lengths, and quantum-mechanical descriptors failed to predict the stability of the cages. However, we derived a simple topological rule that adjacent hexagons on the cage surface resulted in its instability. For this reason, the number of stable nitrogen cages is significantly restricted in comparison with their carbon counterparts. As a rule, smaller clusters are more stable, whereas the earlier proposed large cages collapse at room temperature. The most stable all-nitrogen cages are the N4 and N6 clusters, which can form the van der Waals crystals with densities of 1.23 and 1.36 g/cm3, respectively. The examination of their band structures and densities of electronic states shows that they are both insulators. Their power and sensitivity are not inferior to the modern advanced high-energy nanosystems.

scholarly journals CrystalExplorer: a program for Hirshfeld surface analysis, visualization and quantitative analysis of molecular crystals

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Peter R. Spackman ◽  
Michael J. Turner ◽  
Joshua J. McKinnon ◽  
Stephen K. Wolff ◽  
Daniel J. Grimwood ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Crystal ◽  
Academic Research ◽  
Molecular Crystals ◽  
Hirshfeld Surface ◽  
Quantum Mechanical ◽  
Two Dimensional ◽  
Current Version ◽  
The Past ◽  
Cross Platform

CrystalExplorer is a native cross-platform program supported on Windows, MacOS and Linux with the primary function of visualization and investigation of molecular crystal structures, especially through the decorated Hirshfeld surface and its corresponding two-dimensional fingerprint, and through the visualization of void spaces in the crystal via isosurfaces of the promolecule electron density. Over the past decade, significant changes and enhancements have been incorporated into the program, such as the capacity to accurately and quickly calculate and visualize quantitative intermolecular interactions and, perhaps most importantly, the ability to interface with the Gaussian and NWChem programs to calculate quantum-mechanical properties of molecules. The current version, CrystalExplorer21, incorporates these and other changes, and the software can be downloaded and used free of charge for academic research.

Modelling organic molecular crystals by hybrid quantum mechanical/molecular mechanical embedding

2008 ◽  
Vol 457 (1-3) ◽  
pp. 154-158 ◽  
Author(s):  
Juan Torras ◽  
Stefan Bromley ◽  
Oscar Bertran ◽  
Francesc Illas
Keyword(s):  
Molecular Crystals ◽  
Quantum Mechanical ◽  
Organic Molecular Crystals

Molecular crystals and liquid crystals: new results for t -butyl chloride

1980 ◽  
Vol 290 (1043) ◽  
pp. 567-582 ◽  
Keyword(s):  
Liquid Crystals ◽  
Molecular Crystals ◽  
Quantum Mechanical ◽  
Characteristic Time Scale ◽  
Main Theme ◽  
Butyl Chloride ◽  
Quasielastic Scattering ◽  
Potential Wells ◽  
Crystal Phases

The main theme of this paper is the use of incoherent quasielastic scattering to study molecular reorientational motions in molecular and liquid crystals at temperatures where a classical description is appropriate. The relation to quantum mechanical tunnelling between orientational potential wells of hydrogenous species (e.g. CH 3 , NH + 4 ) is mentioned briefly. The use of this technique is illustrated with a description of the determination of the nature and dynamics of the molecular reorientations in the solid phases of t -butyl chloride. This shows how the measurement of the quasielastic spectrum as a function of scattering vector permits an identification of the type of reorientation and its characteristic time scale, provided this is fast enough to be observed in a neutron experiment (r < 10 -9 s). Finally a brief resume is given of the results that have emerged from such studies about the various molecular motions that characterize and distinguish different liquid crystal phases.

Assessment of Different Quantum Mechanical Methods for the Prediction of Structure and Cohesive Energy of Molecular Crystals

2016 ◽  
Vol 12 (7) ◽  
pp. 3340-3352 ◽  
Author(s):  
Michele Cutini ◽  
Bartolomeo Civalleri ◽  
Marta Corno ◽  
Roberto Orlando ◽  
Jan Gerit Brandenburg ◽  
...  
Keyword(s):  
Cohesive Energy ◽  
Molecular Crystals ◽  
Quantum Mechanical ◽  
Mechanical Methods
Sign in / Sign up

Export Citation Format

Share Document