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
Christmas gift (exclamation) also in southern Pennsylvania, Ohio Valley, West Virginia, and later in northeastern Texas as a simple greeting and recognizing the birth of Christ as a gift. A variant of the tradition is "Christmas Eve gift". The tradition is similar to the "Christmas gift" tradition, but occurs on Christmas Eve. The person being told "Christmas Eve gift!" is expected to present the person saying it to them with a small present, traditionally candy or nuts. The Dictionary of American Regional English traces the first written uses of this version to 1954. Christmas gift (exclamation) "Christmas gift" is an exclamation traced back