scholarly journals The Role of the Solvent in the Condensed-Phase Dynamics and Identity of Chemical Bonds: The Case of the Sodium Dimer Cation in THF

2020 ◽  
Vol 124 (30) ◽  
pp. 6603-6616 ◽  
Author(s):  
Devon R. Widmer ◽  
Benjamin J. Schwartz
Keyword(s):  
Condensed Phase ◽  
Chemical Bonds ◽  
Phase Dynamics ◽  
Sodium Dimer

scholarly journals Protein crystal lattices are dynamic assemblies: the role of conformational entropy in the protein condensed phase

IUCrJ ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 130-140 ◽  
Author(s):  
Margarita Dimova ◽  
Yancho D. Devedjiev
Keyword(s):  
Condensed Phase ◽  
Protein Structures ◽  
Van Der Waals Interactions ◽  
Protein Crystal ◽  
Crystal Formation ◽  
Conformational Entropy ◽  
Crystal Lattices ◽  
Crystal Contacts ◽  
First Time

Until recently, the occurrence of conformational entropy in protein crystal contacts was considered to be a very unlikely event. A study based on the most accurately refined protein structures demonstrated that side-chain conformational entropy and static disorder might be common in protein crystal lattices. The present investigation uses structures refined using ensemble refinement to show that although paradoxical, conformational entropy is likely to be the major factor in the emergence and integrity of the protein condensed phase. This study reveals that the role of shape entropy and local entropic forces expands beyond the onset of crystallization. For the first time, the complete pattern of intermolecular interactions by protein atoms in crystal lattices is presented, which shows that van der Waals interactions dominate in crystal formation.

From Atomic Orbitals to Molecular Orbitals and Chemical Bonds

2020 ◽  
pp. 150-187
Author(s):  
Jochen Autschbach
Keyword(s):  
Hydrogen Molecule ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Basis Set ◽  
Orbital Method ◽  
Chemical Bonds ◽  
Atomic Orbitals ◽  
Hartree Fock ◽  
Generalized Matrix

It is shown how an aufbau principle for atoms arises from the Hartree-Fock (HF) treatment with increasing numbers of electrons. The Slater screening rules are introduced. The HF equations for general molecules are not separable in the spatial variables. This requires another approximation, such as the linear combination of atomic orbitals (LCAO) molecular orbital method. The orbitals of molecules are represented in a basis set of known functions, for example atomic orbital (AO)-like functions or plane waves. The HF equation then becomes a generalized matrix pseudo-eigenvalue problem. Solutions are obtained for the hydrogen molecule ion and H2 with a minimal AO basis. The Slater rule for 1s shells is rationalized via the optimal exponent in a minimal 1s basis. The nature of the chemical bond, and specifically the role of the kinetic energy in covalent bonding, are discussed in details with the example of the hydrogen molecule ion.

Charge distributions and chemical effects. XL. Chemical bonds in benzenoid hydrocarbons

1986 ◽  
Vol 64 (2) ◽  
pp. 404-412 ◽  
Author(s):  
S. Fliszár ◽  
G. Cardinal ◽  
N. A. Baykara
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Atomic Charges ◽  
Chemical Bonds ◽  
Benzenoid Hydrocarbons ◽  
Average Deviation ◽  
Chemical Effects ◽  
Local Charge ◽  
Theoretical Results

Benzenoid hydrocarbons were examined using a bond energy scheme featuring the role of atomic charges. The latter were conveniently deduced from appropriate correlations between theoretical results and 13C nuclear magnetic resonance shifts. Atomization energies calculated in this manner agree with their experimental counterparts to within 0.36 kcal mol-1 (average deviation). It appears that benzenoid hydrocarbons can be efficiently described in terms of local charge density properties. In the absence of any distinctive specific feature characterizing benzenoids, this particular description of chemical bonds ultimately results in a unifying genealogy smoothly relating to one another the various possible types of CC and CH bonds which are formed by sp2 and sp3 carbons.

Flame Retardancy of Polymers: The Role of Specific Reactions in the Condensed Phase

2015 ◽  
Vol 301 (1) ◽  
pp. 9-35 ◽  
Author(s):  
Bernhard Schartel ◽  
Birgit Perret ◽  
Bettina Dittrich ◽  
Michael Ciesielski ◽  
Johannes Krämer ◽  
...  
Keyword(s):  
Condensed Phase ◽  
Flame Retardancy ◽  
Specific Reactions

scholarly journals Condensed Phase Laser Induced Harpoon Reactions

1988 ◽  
Vol 9 (1-3) ◽  
pp. 1-26 ◽  
Author(s):  
Mario E. Fajardo ◽  
R. Withnall ◽  
J. Feld ◽  
F. Okada ◽  
W. Lawrence ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Condensed Phase ◽  
Rare Gas ◽  
Many Body ◽  
Phase Dynamics ◽  
Two Photon ◽  
Radiation Fields ◽  
Electron Transitions ◽  
Charge Transfer Reactions

Laser induced charge transfer reactions of halogens in rare gas solids and liquids provide a powerful means for the study of condensed phase dynamics. Many-body effects with respect to both electronic and nuclear coordinates, and cooperative interactions with radiation fields, are some of the studied phenomena that are highlighted in this article.The pertinence of these ionic reactions to chemistry in solids is demonstrated in photodissociation studies of molecular halogens in rare gas matrices. The coexistence of both delocalized and localized charge transfer states in solid xenon doped with atomic halogens is presented and dynamical consequences—charge separation, self-trapping and energy storage—are discussed. Static and dynamic solvent effects in liquid phase harpoon reactions are considered. The characterization of cooperative excitations— two-photon, two-electron transitions—in liquid solutions is presented.

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