Configuration interactionConfiguration interaction (CI) is a post-Hartree–Fock linear variational method for solving the nonrelativistic Schrödinger equation within the Born–Oppenheimer approximation for a quantum chemical multi-electron system. Mathematically, configuration simply describes the linear combination of Slater determinants used for the wave function. In terms of a specification of orbital occupation (for instance, (1s)2(2s)2(2p)1...), interaction means the mixing (interaction) of different electronic configurations (states).
Multi-configurational self-consistent fieldMulti-configurational self-consistent field (MCSCF) is a method in quantum chemistry used to generate qualitatively correct reference states of molecules in cases where Hartree–Fock and density functional theory are not adequate (e.g., for molecular ground states which are quasi-degenerate with low-lying excited states or in bond-breaking situations). It uses a linear combination of configuration state functions (CSF), or configuration determinants, to approximate the exact electronic wavefunction of an atom or molecule.
Electronic correlationElectronic correlation is the interaction between electrons in the electronic structure of a quantum system. The correlation energy is a measure of how much the movement of one electron is influenced by the presence of all other electrons. Within the Hartree–Fock method of quantum chemistry, the antisymmetric wave function is approximated by a single Slater determinant. Exact wave functions, however, cannot generally be expressed as single determinants.
Matrix (mathematics)In mathematics, a matrix (plural matrices) is a rectangular array or table of numbers, symbols, or expressions, arranged in rows and columns, which is used to represent a mathematical object or a property of such an object. For example, is a matrix with two rows and three columns. This is often referred to as a "two by three matrix", a " matrix", or a matrix of dimension . Without further specifications, matrices represent linear maps, and allow explicit computations in linear algebra.
DeterminantIn mathematics, the determinant is a scalar value that is a function of the entries of a square matrix. It characterizes some properties of the matrix and the linear map represented by the matrix. In particular, the determinant is nonzero if and only if the matrix is invertible and the linear map represented by the matrix is an isomorphism. The determinant of a product of matrices is the product of their determinants (the preceding property is a corollary of this one). The determinant of a matrix A is denoted det(A), det A, or .
Cross-correlationIn signal processing, cross-correlation is a measure of similarity of two series as a function of the displacement of one relative to the other. This is also known as a sliding dot product or sliding inner-product. It is commonly used for searching a long signal for a shorter, known feature. It has applications in pattern recognition, single particle analysis, electron tomography, averaging, cryptanalysis, and neurophysiology. The cross-correlation is similar in nature to the convolution of two functions.
System of linear equationsIn mathematics, a system of linear equations (or linear system) is a collection of one or more linear equations involving the same variables. For example, is a system of three equations in the three variables x, y, z. A solution to a linear system is an assignment of values to the variables such that all the equations are simultaneously satisfied. A solution to the system above is given by the ordered triple since it makes all three equations valid. The word "system" indicates that the equations should be considered collectively, rather than individually.
Matrix exponentialIn mathematics, the matrix exponential is a matrix function on square matrices analogous to the ordinary exponential function. It is used to solve systems of linear differential equations. In the theory of Lie groups, the matrix exponential gives the exponential map between a matrix Lie algebra and the corresponding Lie group. Let X be an n×n real or complex matrix. The exponential of X, denoted by eX or exp(X), is the n×n matrix given by the power series where is defined to be the identity matrix with the same dimensions as .
Matrix decompositionIn the mathematical discipline of linear algebra, a matrix decomposition or matrix factorization is a factorization of a matrix into a product of matrices. There are many different matrix decompositions; each finds use among a particular class of problems. In numerical analysis, different decompositions are used to implement efficient matrix algorithms. For instance, when solving a system of linear equations , the matrix A can be decomposed via the LU decomposition.
AndreaAndrea is a given name which is common worldwide for both males and females, cognate to Andreas, Andrej and Andrew. The name derives from the Greek word ἀνήρ (anēr), genitive ἀνδρός (andrós), that refers to man as opposed to woman (whereas man in the sense of human being is ἄνθρωπος, ánthropos). The original male Greek name, Andréas, represents the hypocoristic, with endearment functions, of male Greek names composed with the andr- prefix, like Androgeos (man of the earth), Androcles (man of glory), Andronikos (man of victory).
AutocorrelationAutocorrelation, sometimes known as serial correlation in the discrete time case, is the correlation of a signal with a delayed copy of itself as a function of delay. Informally, it is the similarity between observations of a random variable as a function of the time lag between them. The analysis of autocorrelation is a mathematical tool for finding repeating patterns, such as the presence of a periodic signal obscured by noise, or identifying the missing fundamental frequency in a signal implied by its harmonic frequencies.
Exact solutions in general relativityIn general relativity, an exact solution is a solution of the Einstein field equations whose derivation does not invoke simplifying assumptions, though the starting point for that derivation may be an idealized case like a perfectly spherical shape of matter. Mathematically, finding an exact solution means finding a Lorentzian manifold equipped with tensor fields modeling states of ordinary matter, such as a fluid, or classical non-gravitational fields such as the electromagnetic field.
San Andreas (film)San Andreas is a 2015 American disaster film directed by Brad Peyton and written by Carlton Cuse, with Andre Fabrizio and Jeremy Passmore receiving story credit. The film stars Dwayne Johnson, in the lead role, Carla Gugino, Alexandra Daddario, Ioan Gruffudd, Archie Panjabi and Paul Giamatti. Its plot centers on a massive earthquake caused by the San Andreas Fault, devastating the West Coast of the United States. Principal photography of the film started on April 22, 2014, in Queensland, Australia, and wrapped up on July 28 in San Francisco.
Small Island (novel)Small Island is a 2004 prize-winning novel by British author Andrea Levy, her fourth novel. The novel is based on four main characters—Hortense, Queenie, Gilbert and Bernard—and the story is told from each of their points of view. Mainly set in 1948, the plot focuses on the diaspora of Jamaican immigrants, who, escaping economic hardship on their own "small island", move to England, the Mother Country, for which the men have fought during World War II.
La prepago– La prepago is a Colombian telenovela produced by Sony Pictures Television for RCN Televisión, based on the popular book written by Carlos Duplat, Las memorias de Andrea. Lilo de la Vega and Andrés Sandoval stars as the protagonists, while Julián Román, Alejandro Aguilar and Luis Eduardo Arango star as the antagonists. Lilo de la Vega - Ana Lucia Barrera / Andrea Andrés Sandoval - David Julián Román - Wilson Natalia Durán - Carolina Juliana Robledo - Paola Cabal Luis Eduardo Arango - Reinaldo “Don Rey” Kat
Mass numberThe mass number (symbol A, from the German word: Atomgewicht, "atomic weight"), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximately equal to the atomic (also known as isotopic) mass of the atom expressed in atomic mass units. Since protons and neutrons are both baryons, the mass number A is identical with the baryon number B of the nucleus (and also of the whole atom or ion).
Atomic numberThe atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number (np) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ordinary chemical elements. In an ordinary uncharged atom, the atomic number is also equal to the number of electrons.
Atomic orbitalIn atomic theory and quantum mechanics, an atomic orbital (ˈɔːrbɪtəl) is a function describing the location and wave-like behavior of an electron in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus. The term atomic orbital may also refer to the physical region or space where the electron can be calculated to be present, as predicted by the particular mathematical form of the orbital.
The Invisibles (film)The Invisibles (German: Die Unsichtbaren – Wir wollen leben) is a 2017 German docudrama by Claus Räfle. The film presents the experience of four Jewish teenagers who survived the Holocaust by going into hiding in Berlin during World War II. It interweaves personal interviews, dramatic reenactment, archival footage, and narration. The main actors are Max Mauff, Alice Dwyer, Ruby O. Fee and Aaron Altaras. The film recounts the struggle of Cioma Schönhaus, Hanni Lévy, Eugen Friede and Ruth Arndt-Gumpel to survive their persecution as Jews in Berlin from 1942 to 1945.
Fluid solutionIn general relativity, a fluid solution is an exact solution of the Einstein field equation in which the gravitational field is produced entirely by the mass, momentum, and stress density of a fluid. In astrophysics, fluid solutions are often employed as stellar models. (It might help to think of a perfect gas as a special case of a perfect fluid.) In cosmology, fluid solutions are often used as cosmological models.
