نتایج جستجو برای: chemical bond
تعداد نتایج: 440732 فیلتر نتایج به سال:
abstract the influence of cation?? and anion?? interactions on the strength and nature of n…h hydrogen bond has been investigated by quantum chemical calculations in s-triazine…3hf complex. ab initio calculations were performed at mp2/6-311++g(d,p) level of theory. the natural bond orbital (nbo) analysis and the bader’s quantum theory of atoms in molecules (aim) were also used to elucidate t...
In dynamic force spectroscopy, a (bio-)molecular complex is subjected to a steadily increasing force until the chemical bond breaks. Repeating the same experiment many times results in a broad distribution of rupture forces, whose quantitative interpretation represents a formidable theoretical challenge. In this study we address the situation that more than a single molecular bond is involved i...
The chemical bond and structural features for the most important classes of solid products obtained by reacting chalcogen donors with dihalogens and interhalogens are reviewed. Particular attention is paid to the information the FT-Raman spectroscopy can confidently give about each structural motif considered in the absence of X-ray structural analyses.
Electron motion in chemical bonds occurs on an attosecond timescale. This ultrafast motion can be driven by strong laser fields. Ultrashort asymmetric laser pulses are known to direct electrons to a certain direction. But do symmetric laser pulses destroy symmetry in breaking chemical bonds? Here we answer this question in the affirmative by employing a two-particle coincidence technique to inv...
We explore explicit electron pair behaviour within the chemical bond (and lone pairs) by calculating the probability distribution for the center-of-mass (extracule) of an electron pair described by single localized orbitals. Using Edmiston-Ruedenberg localized orbitals in a series of 61 chemical systems, we demonstrate the utility of the extracule density as an interpretive tool in chemistry. B...
From a simplified version of the mathematical structure of the strong coupling limit of the exact exchange-correlation functional, we construct an approximation for the electronic repulsion energy at physical coupling strength, which is fully nonlocal. This functional is self-interaction free and yields energy densities within the definition of the electrostatic potential of the exchange-correl...
Conceiving a molecule as being composed of smaller molecular fragments, or subunits, is one of the pillars of the chemical and physical sciences and leads to productive methods in quantum chemistry. Using a fragmentation scheme, efficient algorithms can be proposed to address problems in the description of chemical bond formation and breaking. We present a formally exact time-dependent density ...
ion molecules with general chemical formula as [li(h2o)] (n=1,2,3), have been chosen as model species toinvestigate the chemical properties of hydrated lithium cations. the rhf(scvs)/ugbs level of calculationhas been used for obtaining equilibrium geometries and rho(r) functions (electron density distributions). by theaid of fundamental physical theorems implemented in quantum theory of atoms i...
When a chemical bond is broken in a direct dissociation reaction, the process is so rapid that it has generally been considered instantaneous and thus unmeasurable. However, the bond does persist for times on the order of 10(-13) seconds after the photon has been absorbed. Femtosecond (10(-15) second) laser techniques can be used to directly clock this process, which describes the dynamics of t...
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