Muffin-tin approximation Muffin-tin approximation The muffin-tin approximation is a shape approximation of the potential well in an crystal lattice. It is most commonly employed in quantum mechanical simulations of the electronic band structure in solids. The approximation was proposed by John C. Slater. Augmented plane wave method (APW) is a method which uses muffin-tin approximation. It is a method to approximate the energy states of an electron in a crystal lattice. The basic approximation lies in the potential in which the potential is assumed to be spherically symmetric in the muffin-tin region and constant in the interstitial region. Wave functions (the augmented
Wedding anniversary widely marked as her Diamond Jubilee. The origins of the current gift conventions date to 1937. Before that, only the 1st, 5th, 10th, 15th, 20th, 25th, 50th, and 75th anniversaries had an associated gift. In 1937, the American National Retail Jeweler Association (now known as Jewelers of America as a result of an organizational merger) introduced an expanded list of gifts. The revamped list gave a gift for each year up to the 25th, and then for every fifth anniversary after that. Lists of wedding anniversary gifts vary by country. The traditional and modern U.S. versions were compiled by librarians