The figure shows two different integration "grids," a standard rectangular grid versus an contour-by-contour grid. The Materials Simulation Group (msg.byu.edu) is exploring competing schemes for speeding up the integration of electron bands in materials. An important part of "first-principles" materials calculations involves integrating over the occupied electron states, the so-called "band energy integration." This is the primary source of error in first-principles calculations of solids. Improving this integration would have a dramatic impact on computational simulations of metallic systems.
The first robotic telescope has been installed on the observation deck of the Orson Pratt Observatory. The first images where taken through the telescope on May 21, 2017 during a daytime practice run. This image of the moon was taken through a narrow H-alpha filter.
This image was secured during the installation of the 0.9-m telescope at the BYU West Mountain Observatory. Data for this image is from August 27, 2009. This was the first night that a CCD detector had been mounted on the telescope so that imaging was possible. This 'First Light' image shows the globular cluster known as M15 in the constellation of Pegasus. The distance to this cluster is more than 33,000 light years and yet individual stars are easily resolved all through the cluster. Globular cluster stars have an extremely low abundance of heavy elements compared to stars found in the solar neighborhood and represent the oldest population of stars known in the Galaxy. Stars in M15 are known to have a heavy element abundance more than 100 times lower than the Sun. It is interesting to note the many cool red giant stars that are visible in the cluster as well as a large number of evolved horizontal branch stars that are blue in color. Many of the horizontal branch stars are known to be RR Lyrae variable stars that are useful as distance indicators since it is possible to determine their luminosity and compare that to their apparent magnitude measured from observed images. The color image processing for this picture is the work of renowned image processing expert, Dr. Rob Gendler.
An important part of "first-principles" materials calculations involves integrating over the occupied electron states, the so-called "band energy integration." This is the primary source of error in first-principles calculations of solids. Improving this integration would have a dramatic impact on computational simulations of metallic systems. The right half of the figure shows the "Brillouin zone," the periodic tile of the electron bands. The left half shows a sample band structure. Visualization is difficult because the bands are a multivalued, three-dimensional function. The shown function is a single-valued function with a cut-away to show the function variation as a function of position.
The small black spot projected on the Sun just above the foreground clouds in Provo is caused by the planet Venus as it transits for the last time this century. The transits of Venus come in pairs separated by eight years that only occur after a period of 105 or 122 years without a transit visible from the Earth. If you missed this event, the next opportunity will be in December of 2117. Finding the transit of an Earth sized planet across a stellar photosphere was the primary mission of the Kepler spacecraft as it searched for extrasolar planets up through August 2013. The difficulty of this mission is apparent when you note the tiny fraction of the Sun's light that is blocked by the transit of a planet the size of Venus.
23 Sep, Today
24 Sep, Sunday
27 Sep, Wednesday
Brent Reichman, Kent Gee, Traci Neilsen, and Alan Wall et al. recently published an article titled "Acoustical Environment During F-35B Vertical Landing Operations" in Journal of Aircraft. Click on the image above to read it.
A Conjunction of Comets: A conjunction of comets is captured in this pretty star field from the morning of September 17. Discovered in July by a robotic sky survey searching for supernovae, comet C/2017 O1 ASASSN is at the lower left....
This photograph and Description come from NASA's Astronomy Picture of the Day web site.