The new server hosting the indexing scripts seems to have a more strict memory usage, and the code base really needs an overhaul. Practically, this meant that the indexing failed because of running out of memory, causing the system to not index at all anymore. I have done some clean up, and Cb is back online.
Some of you noted and reported that Chemical blogspace has not seen any updates since March 4. I can confirm this problem, which is likely due to server movement on our ISP. My apologies for the inconvenience, and I hope to restore indexing on short notice, but given other priorities, I cannot give an ETA yet.
A bit more than four hands full of new blogs in the four months since New Blogs #11. Importantly, I have disabled the Accelrys blog in favor if the blogs of its individual contributors, Dana, George, Gerhard, Max, Nancy and Shikna. This is not to boost the number of blogs, but merely reflects that Cb focuses on personal (accountable) opinions and not corporate blog (which is often polluted with to much advertisement).
Would you object to seeing Google Adsense ads on the Cb website? The money it would bring up would be donated to a charity involved in promoting Open Science. Please let us know, either as comment on this blog item or by email.
Looking forward to hearing from you!
Crystal structure.In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. A crystal structure is composed of a motif, a set of atoms arranged in a particular way, and a lattice. Motifs are located upon the points of a lattice, which is an array of points repeating periodically in three dimensions. The points can be thought of as forming identical tiny boxes, called unit cells, that fill the space of the lattice. The lengths of the edges of a unit cell and the angles between them are called the lattice parameters. The symmetry properties of the crystal are embodied in its space group. A crystal's structure and symmetry play a role in determining many of its properties, such as cleavage, electronic band structure, and optical properties.
Unit cell.The crystal structure of a material or the arrangement of atoms in a crystal structure can be described in terms of its unit cell. The unit cell is a tiny box containing one or more motifs, a spatial arrangement of atoms. The units cells stacked in three-dimensional space describes the bulk arrangement of atoms of the crystal. The unit cell is given by its lattice parameters, the length of the cell edges and the angles between them, while the positions of the atoms inside the unit cell are described by the set of atomic positions (xi,yi,zi) measured from a lattice point.Although there are an infinite number of ways to specify a unit cell, for each crystal structure there is a conventional unit cell, which is chosen to display the full symmetry of the crystal (see below). However, the conventional unit cell is not always the smallest possible choice. A primitive unit cell of a particular crystal structure is the smallest possible volume one can construct with the arrangement of atoms in the crystal such that, when stacked, completely fills the space. This primitive unit cell does not always display all the symmetries inherent in the crystal. A Wigner-Seitz cell is a particular kind of primitive cell which has the same symmetry as the lattice. In a unit cell each atom has an identical environment when stacked in 3 dimensional space. In a primitive cell, each atom may not have the same environment.
Not that the last two weeks has seen a boost on blog submissions to Chemical blogspace; just that I was not really finished with New Blogs #10.
