Some valency oriented molecular invariants of certain networks.

Background: The valency of an atom in a molecular structure is the number of its neighboring atoms. A large number of valency based molecular invariants have been conceived, which correlate certain physio-chemical properties like boiling point, stability, strain energy and many more of chemical compounds. Objective: Our aim is to study the valency based molecular invariants for four hexa chemical structures, namely hexagonal network, honeycomb network, oxide network and silicate sheet network. Method: We use the technique of atom-bonds partition according to the valences of atoms to find results. Results: Exact values of valency-based molecular invariants, namely the Randić index, atom bond connectivity index, geometric arithmetic index, harmonic index, Zagreb indices, Zagreb polynomials, F-index and F-polynomial are found for four hexa chemical structures.

Innsbruckite, Mn33(Si2O5)14(OH)38 – a new mineral from the Tyrol, Austria

A description of the new mineral innsbruckite, Mn33(Si2O5)14(OH)38, a hydrous manganese phyllosilicate found in Tyrol, Austria is given. The crystal structure was determined by singlecrystal synchrotron radiation diffraction experiments at the X06DA beamline at the Swiss Light Source (Paul Scherrer Institute, Villigen, Switzerland). The space group is Cm and lattice parameters are a = 17.2760(19), b = 35.957(5), c = 7.2560(8) Å , β = 91.359(7)º, V = 4506.1(10) Å3, Z = 2. Innsbruckite belongs to the group of modulated 1:1 layer silicates and is chemically and structurally quite closely related to bementite, Mn7(Si2O5)3(OH)8. The chemical analysis revealed a close to ideal composition with only minor amounts of Al, Fe and Mg. Using Liebau’s nomenclature for silicate classification the silicate anion can be described as an unbranched siebener single layer. Innsbruckite shows a complex topology of the silicate sheet, exhibiting 4-, 5-, 6- and 8-membered rings. The silicate sheet is fully characterized using vertex symbols, and its topology is compared to those in other complex sheet silicates. Furthermore, the structural investigation is complemented with Raman spectroscopic studies.

ON OSCILLATORS IN PHYLLOSILICATE EXCITABLE AUTOMATA

Phyllosilicate is a sheet of silicate tetrahedra bound by basal oxygens. A phyllosilicate excitable automaton is a regular network of finite state machines, which mimics structure of a silicate sheet. A node of the silicate sheet is an automaton, which takes resting, excited and refractory states, and updates its state in discrete time depending on a sum of excited states of its three (silicon automata) or six (oxygen automata) closest neighbors. Oscillator is a localized compact configuration of nonquiescent states which undergoes finite growth and modification but returns to its original state in a finite number of steps. We show that phyllosilicate excitable automata exhibit waves and oscillating localizations (oscillators) dynamics. Basic types of oscillators are classified and characterized.

Raman Microprobe Spectra and Vibrational Mode Assignments of Talc

The Raman spectra of talc microparticles have been obtained with the Raman microprobe over the frequency range 100 to 3800 cm−1. The vibrational modes are discussed in terms of an idealized unit cell (1-M polymorph) of C2h symmetry. An electrostatic dipole-dipole interaction is used to compare the Raman and infrared active branches. Assignments of the Raman active stretching modes of the silicate sheet are found to support previous infrared assignments. Estimates of intrasheet dipole-dipole interactions are obtained.