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Ivar Waller
Ivar Waller (11 June 1898 – 12 April 1991) was a Swedish professor of theoretical physics at Uppsala University. He developed the theory of X-ray scattering by lattice vibrations of a crystal, building upon the prior work of Peter Debye. The Debye–Waller factor, which he introduced in his doctoral thesis in 1925, is the definitive treatment of the effect of thermal vibrations in X-ray crystallography. He was a member of the Royal Swedish Academy of Sciences from 1945, and the Nobel Committee for Physics 1945-1972. One of his notable doctoral students was the quantum chemist Per-Olov Löwdin Per-Olov Löwdin (October 28, 1916 – October 6, 2000) was a Swedish physicist, professor at the University of Uppsala from 1960 to 1983, and in parallel at the University of Florida until 1993. A former graduate student under Ivar Waller, Löwd .... External links Obituary in Journal of Applied Crystallography, 1992 {{DEFAULTSORT:Waller, Ivar 1898 births 1991 deaths Swedish physi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uppsala University
Uppsala University ( sv, Uppsala universitet) is a public university, public research university in Uppsala, Sweden. Founded in 1477, it is the List of universities in Sweden, oldest university in Sweden and the Nordic countries still in operation. The university rose to significance during the rise of Swedish Empire, Sweden as a great power at the end of the 16th century and was then given a relative financial stability with a large donation from King Gustavus Adolphus of Sweden, Gustavus Adolphus in the early 17th century. Uppsala also has an important historical place in Swedish national culture, identity and for the Swedish establishment: in historiography, literature, politics, and music. Many aspects of Swedish academic culture in general, such as the white student cap, originated in Uppsala. It shares some peculiarities, such as the student nation system, with Lund University and the University of Helsinki. Uppsala belongs to the Coimbra Group of European universities a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Scattering
X-ray scattering techniques are a family of non-destructive analytical techniques which reveal information about the crystal structure, chemical composition, and physical properties of materials and thin films. These techniques are based on observing the scattered intensity of an X-ray beam hitting a sample as a function of incident and scattered angle, polarization, and wavelength or energy. Note that X-ray diffraction X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ... is now often considered a sub-set of X-ray scattering, where the scattering is elastic and the scattering object is crystalline, so that the resulting pattern contains sharp spots analyzed by X-ray crystallography (as in the Figure). However, both scattering and diffraction are related general phenomena and the dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Debye
Peter Joseph William Debye (; ; March 24, 1884 – November 2, 1966) was a Dutch-American physicist and physical chemist, and Nobel laureate in Chemistry. Biography Early life Born Petrus Josephus Wilhelmus Debije in Maastricht, Netherlands, Debye enrolled in the Aachen University of Technology in 1901. In 1905, he completed his first degree in electrical engineering. He published his first paper, a mathematically elegant solution of a problem involving eddy currents, in 1907. At Aachen, he studied under the theoretical physicist Arnold Sommerfeld, who later claimed that his most important discovery was Peter Debye. In 1906, Sommerfeld received an appointment at Munich, Bavaria, and took Debye with him as his assistant. Debye got his Ph.D. with a dissertation on radiation pressure in 1908. In 1910, he derived the Planck radiation formula using a method which Max Planck agreed was simpler than his own. In 1911, when Albert Einstein took an appointment as a professor at Prague ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Debye–Waller Factor
The Debye–Waller factor (DWF), named after Peter Debye and Ivar Waller, is used in condensed matter physics to describe the attenuation of x-ray scattering or coherent neutron scattering caused by thermal motion. It is also called the B factor, atomic B factor, or temperature factor. Often, "Debye–Waller factor" is used as a generic term that comprises the Lamb–Mössbauer factor of incoherent neutron scattering and Mössbauer spectroscopy. The DWF depends on the scattering vector q. For a given q, DWF(q) gives the fraction of elastic scattering; 1 – DWF(q) correspondingly gives the fraction of inelastic scattering. (Strictly speaking, this probability interpretation is not true in general.) In diffraction studies, only the elastic scattering is useful; in crystals, it gives rise to distinct Bragg reflection peaks. Inelastic scattering events are undesirable as they cause a diffuse background — unless the energies of scattered particles are analysed, in which case they c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-ray Crystallography
X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their crystallographic disorder, and various other information. Since many materials can form crystals—such as salts, metals, minerals, semiconductors, as well as various inorganic, organic, and biological molecules—X-ray crystallography has been fundamental in the development of many scientific fields. In its first decades of use, this method determined the size of atoms, the lengths and types of chemical bonds, and the atomic-scale differences among various mat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Royal Swedish Academy Of Sciences
The Royal Swedish Academy of Sciences ( sv, Kungliga Vetenskapsakademien) is one of the Swedish Royal Academies, royal academies of Sweden. Founded on 2 June 1739, it is an independent, non-governmental scientific organization that takes special responsibility for promoting natural sciences and mathematics and strengthening their influence in society, whilst endeavouring to promote the exchange of ideas between various disciplines. The goals of the academy are: * to be a forum where researchers meet across subject boundaries, * to offer a unique environment for research, * to provide support to younger researchers, * to reward outstanding research efforts, * to communicate internationally among scientists, * to advance the case for science within society and to influence research policy priorities * to stimulate interest in mathematics and science in school, and * to disseminate and popularize scientific information in various forms. Every year, the academy awards the Nobel Priz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nobel Committee For Physics
The Nobel Committee for Physics is the Nobel Committee responsible for proposing laureates for the Nobel Prize for Physics.The Nobel Committee for Physics accessed 2022-05-31 The Nobel Committee for Physics is appointed by the . It usually consists of Swedish professors of physics who are members of the Academy, although the Academy in principle could appoint anyone to the Committee. The Committee is a working body without decision power, and the final decision to award the Nobel Prize for Physics is taken by the entire Royal Swedish Academy of Sciences, after having a first dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Per-Olov Löwdin
Per-Olov Löwdin (October 28, 1916 – October 6, 2000) was a Swedish physicist, professor at the University of Uppsala from 1960 to 1983, and in parallel at the University of Florida until 1993. A former graduate student under Ivar Waller, Löwdin formulated in 1950 the symmetric orthogonalization scheme for atomic and molecular orbital calculations, greatly simplifying the tight-binding method. This scheme is the basis of the zero-differential overlap (ZDO) approximation used in semiempirical theories. In 1956 he introduced the canonical orthogonalization scheme, which is optimal for eliminating approximate linear dependencies of a basis set. These orthogonalization procedures are widely used today in all modern quantum chemistry calculations. He is also credited with the use of fat symbols for matrices, making easy the derivation of several theorems of quantum mechanics. The famous 'Löwdin's pairing theorem' used in restricted open-shell Hartree–Fock (ROHF), unrestricted H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1898 Births
Events January–March * January 1 – New York City annexes land from surrounding counties, creating the City of Greater New York as the world's second largest. The city is geographically divided into five boroughs: Manhattan, Brooklyn, Queens, The Bronx and Staten Island. * January 13 – Novelist Émile Zola's open letter to the President of the French Republic on the Dreyfus affair, ''J'Accuse…!'', is published on the front page of the Paris daily newspaper ''L'Aurore'', accusing the government of wrongfully imprisoning Alfred Dreyfus and of antisemitism. * February 12 – The automobile belonging to Henry Lindfield of Brighton rolls out of control down a hill in Purley, London, England, and hits a tree; thus he becomes the world's first fatality from an automobile accident on a public highway. * February 15 – Spanish–American War: The USS ''Maine'' explodes and sinks in Havana Harbor, Cuba, for reasons never fully established, killing 266 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1991 Deaths
File:1991 Events Collage.png, From left, clockwise: Boris Yeltsin, 1991 Russian presidential election, elected as Russia's first President of Russia, president, waves the new flag of Russia after the 1991 Soviet coup d'état attempt, orchestrated by Soviet Union, Soviet hardliners; Mount Pinatubo 1991 eruption of Mount Pinatubo, erupts in the Philippines, making it the List of large historical volcanic eruptions, second-largest Types of volcanic eruptions, volcanic eruption of the 20th century; MTS Oceanos sinks off the coast of South Africa, but the crew notoriously abandons the vessel before the passengers are rescued; Dissolution of the Soviet Union: The Flag of the Soviet Union, Soviet flag is lowered from the Kremlin for the last time and replaced with the flag of the Russian Federation; The United States and soon-to-be dissolved Soviet Union sign the START I Treaty; A tropical cyclone 1991 Bangladesh cyclone, strikes Bangladesh, killing nearly 140,000 people; Lauda Air Flight ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swedish Physicists
Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by the Swedish language * Swedish people or Swedes, persons with a Swedish ancestral or ethnic identity ** A national or citizen of Sweden, see demographics of Sweden ** Culture of Sweden * Swedish cuisine See also * * Swedish Church (other) * Swedish Institute (other) * Swedish invasion (other) * Swedish Open (other) Swedish Open is a tennis tournament. Swedish Open may also refer to: *Swedish Open (badminton) * Swedish Open (table tennis) *Swedish Open (squash) *Swedish Open (darts) The Swedish Open is a darts tournament established in 1969, held in Malmà ... {{disambig Language and nationality disambiguation pages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
