Phonons in fcc Strontium

A more realistic model, requiring a few parameters to explain the interactions among distant neighbours and valid to various crystallographic structures, is developed to study the phonon dispersion in fcc metals the model free from usual fitting procedure, is employed to obtain phonon dispersion in fcc stiontium, which has attracted scant attention so far .The computed results showing good agreement with the recent experimental findings lend reliability and credibility to the theory

Charge Delocalization in Self-Assembled Mixed-Valence Aromatic Cation Radicals

The spontaneous assembly of aromatic cation radicals (D+•) with their neutral counterpart (D) affords dimer cation radicals (D2+•). The intermolecular dimeric cation radicals are readily characterized by the appearance of an intervalence charge-resonance transition in the NIR region of their electronic spectra and by ESR spectroscopy. The X-ray crystal structure analysis and DFT calculations of a representative dimer cation radical (i.e., the octamethylbiphenylene dimer cation radical) have established that a hole (or single positive charge) is completely delocalized over both aromatic moieties. The energetics and the geometrical considerations for the formation of dimer cation radicals is deliberated with the aid of a series of cyclophane-like bichromophoric donors with drastically varied interplanar angles between the cofacially arranged aryl moieties. X-ray crystallography of a number of mixed-valence cation radicals derived from monochromophoric benzenoid donors established that they generally assemble in 1D stacks in the solid state. However, the use of polychromophoric intervalence cation radicals, where a single charge is effectively delocalized among all of the chromophores, can lead to higher-order assemblies with potential applications in long-range charge transport. As a proof of concept, we show that a single charge in the cation radical of a triptycene derivative is evenly distributed on all three benzenoid rings and this triptycene cation radical forms a 2D electronically coupled assembly, as established by X-ray crystallography

(3E,5E)-1-Benzyl-3,5-bis­(2-fluoro­benzyl­idene)piperidin-4-one

The inversion-related mol­ecules of the title compound, C26H21F2NO, associate into closed dimeric subunits via co-operative C—H⋯π inter­actions. Two non-classical C—H⋯O and one C—H⋯N intra­molecular hydrogen bonds are also found in the crystal structure. The piperidin-4-one ring adopts a sofa conforamtion with the 1-benzyl group in the equatorial position, and the equiplanar fluoro­phenyl substituents in the 3- and 5-positions stretched out on either side. The 1-benzyl group is disposed towards the substituent in the 6th position of the piperidin-4-one ring. The 3,5-diene units possess E configurations

3-(7,8,13,14-Tetra­hydrodi­benzo­[a,i]phen­an­thridin-5-yl)benzene-1,2-diol

In the title compound, C27H21NO2, the half-chair conformation of the alicyclic rings gives rise to a slightly folded structure of the central tricyclic tetra­hydrophenanthridine unit. Tandem intra­molecular O—H⋯N and O—H⋯O hydrogen bonds give rise to adjacent S(6) and S(5) rings, respectively, which dictate the conformation of the 5-aryl substituent. In the crystal structure, an inter­molecular C—H⋯O contact generates chains parallel to [101]. Short O—H⋯π and C—H⋯π contacts are also observed

Cohesion, Elastic Constants and Vibrational Mechanics of Fcc Platinum

A model in real space has been developed by extending the generalized form of the exponential potential known as extended generalized exponential potential (EGEP) to account for (a) the correct nature of repulsive and attractive components of forces for all the separations in general and that of small separations in particular, (b) the three-body forces such as volume forces in an indirect way in the framework of EGEP through the parameter n, (c) the dielectric screening functions in an alternative and simpler form through the parameter m. The model is employed to compute the cohesive energy, second-order elastic constants and phenon spectra for fcc platinum. The predictions show promising agreement with experimental findings.Author Affiliation: Divesh Verma A. F. School of Engineering and Technology, Dhauj-121 004, Haryana, India M L Verma* and A Verma Department of Physics, GGDSD College, Palwal-121 102, Haryana, India and R P S Rathore Department of Physics, B.M.A.S. Engineering College, Agra-282 002, Uttar Pradesh, India1.A. F. School of Engineering and Technology, Dhauj-121 004, Haryana, India 2.Department of Physics, GGDSD College, Palwal-121 102, Haryana, India 3.Department of Physics, B.M.A.S. Engineering College, Agra-282 002, Uttar Pradesh, Indi