Molecular physics is the study of the physical properties of molecules and molecular dynamics. The field overlaps significantly with physical chemistry, chemical physics, and quantum chemistry. It is often considered as a sub-field of atomic, molecular, and optical physics. Research groups studying molecular physics are typically designated as one of these other fields. Molecular physics addresses phenomena due to both molecular structure and individual atomic processes within molecules. Like atomic physics, it relies on a combination of classical and quantum mechanics to describe interactions between electromagnetic radiation and matter. Experiments in the field often rely heavily on techniques borrowed from atomic physics, such as spectroscopy and scattering.
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👉 Molecular physics in the context of Université Paris-Saclay
Paris-Saclay University (French: Université Paris-Saclay, pronounced [ynivɛʁsite paʁi saklɛ]) is a combined technological research institute and public research university in Orsay, France. Paris-Saclay was established in 2019 after the merger of four technical grandes écoles, as well as several technological institutes, engineering schools, and research facilities; giving it fifteen constituent colleges with over 48,000 students combined.
With the merger, the French government has explicitly voiced their wish to rival top American technological research institutes, such as MIT. The university has over 275 laboratories in particle physics, nuclear physics, astrophysics, atomic physics and molecular physics, condensed matter physics, theoretical physics, electronics, nanoscience and nanotechnology. It is part of the larger Paris-Saclay cluster, which is a research-intensive academic campus encompassing Paris-Saclay University, the Polytechnic Institute of Paris, combined with a business cluster for high-technology corporations. Paris-Saclay notably also includes the Institut des Hautes Études Scientifiques, where many contributions to the development of modern mathematics have been made, among them modern algebraic geometry and catastrophe theory.
- ⭐ Core Definition: Molecular physics
- 👉 Molecular physics in the context of Université Paris-Saclay
- Molecular physics in the context of Force field (chemistry)
- Molecular physics in the context of Van der Waals force
- Molecular physics in the context of Contour length
- Molecular physics in the context of Nuclear magnetic resonance
- Molecular physics in the context of Edward Teller
- Molecular physics in the context of Born–Oppenheimer approximation
Molecular physics in the context of Force field (chemistry)
In the context of chemistry, molecular physics, physical chemistry, and molecular modelling, a force field is a computational model that is used to describe the forces between atoms (or collections of atoms) within molecules or between molecules as well as in crystals. Force fields are a variety of interatomic potentials. More precisely, the force field refers to the functional form and parameter sets used to calculate the potential energy of a system on the atomistic level. Force fields are usually used in molecular dynamics or Monte Carlo simulations. The parameters for a chosen energy function may be derived from classical laboratory experiment data, calculations in quantum mechanics, or both. Force fields utilize the same concept as force fields in classical physics, with the main difference being that the force field parameters in chemistry describe the energy landscape on the atomistic level. From a force field, the acting forces on every particle are derived as a gradient of the potential energy with respect to the particle coordinates.
A large number of different force field types exist today (e.g. for organic molecules, ions, polymers, minerals, and metals). Depending on the material, different functional forms are usually chosen for the force fields since different types of atomistic interactions dominate the material behavior.
Molecular physics in the context of Van der Waals force
In molecular physics and chemistry, the van der Waals force (sometimes van der Waals' force) is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical electronic bond; they are comparatively weak and therefore more susceptible to disturbance. The van der Waals force quickly vanishes at longer distances between interacting molecules.
Named after Dutch physicist Johannes Diderik van der Waals, the van der Waals force plays a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics. It also underlies many properties of organic compounds and molecular solids, including their solubility in polar and non-polar media.
Molecular physics in the context of Contour length
Contour length is a term used in molecular physics. The contour length of a polymer chain (a big molecule consisting of many similar smaller molecules) is its length at maximum physically possible extension.
Contour length is equal to the product of the number of segments of polymer molecule(n) and its length(l).
Molecular physics in the context of Nuclear magnetic resonance
Nuclear magnetic resonance (NMR) is a physical phenomenon in which nuclei in a strong constant magnetic field are disturbed by a weak oscillating magnetic field (in the near field) and respond by producing an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. This process occurs near resonance, when the oscillation frequency matches the intrinsic frequency of the nuclei, which depends on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved; in practical applications with static magnetic fields up to ca. 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). NMR results from specific magnetic properties of certain atomic nuclei. High-resolution nuclear magnetic resonance spectroscopy is widely used to determine the structure of organic molecules in solution and study molecular physics and crystals as well as non-crystalline materials. NMR is also routinely used in advanced medical imaging techniques, such as in magnetic resonance imaging (MRI). The original application of NMR to condensed matter physics is nowadays mostly devoted to strongly correlated electron systems. It reveals large many-body couplings by fast broadband detection and should not be confused with solid state NMR, which aims at removing the effect of the same couplings by Magic Angle Spinning techniques.
The most commonly used nuclei are
H and
C, although isotopes of many other elements, such as
F,
P, and
Si, can be studied by high-field NMR spectroscopy as well. In order to interact with the magnetic field in the spectrometer, the nucleus must have an intrinsic angular momentum and nuclear magnetic dipole moment. This occurs when an isotope has a nonzero nuclear spin, meaning an odd number of protons and/or neutrons (see Isotope). Nuclides with even numbers of both have a total spin of zero and are therefore not NMR-active.
Molecular physics in the context of Edward Teller
Edward Teller (Hungarian: Teller Ede; January 15, 1908 – September 9, 2003) was a Hungarian-American theoretical physicist and chemical engineer who is known colloquially as "the father of the hydrogen bomb" and one of the creators of the Teller–Ulam design inspired by Stanisław Ulam. He had a volatile personality, and was "driven by his megaton ambitions, had a messianic complex, and displayed autocratic behavior." He devised a thermonuclear Alarm Clock bomb with a yield of 1000 MT (1 GT of TNT) and proposed delivering it by boat or submarine to incinerate a continent.
Born in Austria-Hungary in 1908, Teller emigrated to the US in the 1930s, one of the many so-called "Martians", a group of Hungarian scientist émigrés. He made numerous contributions to nuclear and molecular physics, spectroscopy, and surface physics. His extension of Enrico Fermi's theory of beta decay, in the form of Gamow–Teller transitions, provided an important stepping stone in its application, while the Jahn–Teller effect and Brunauer–Emmett–Teller (BET) theory have retained their original formulation and are mainstays in physics and chemistry. Teller analyzed his problems using basic principles of physics and often discussed with his cohorts to make headway through difficult problems. This was seen when he worked with Stanislaw Ulam to get a workable thermonuclear fusion bomb design, but later temperamentally dismissed Ulam's aid. Herbert York stated that Teller utilized Ulam's general idea of compressive heating to start thermonuclear fusion to generate his own sketch of a workable "Super" bomb. Before Ulam's idea, Teller's classical Super was essentially a system for heating uncompressed liquid deuterium to the point, Teller hoped, that it would sustain thermonuclear burning. It was, in essence, a simple idea from physical principles, which Teller pursued with a ferocious tenacity, even if he was wrong and shown that it would not work. To get support from Washington for his Super weapon project, Teller proposed a thermonuclear radiation implosion experiment as the "George" shot of Operation Greenhouse.
Molecular physics in the context of Born–Oppenheimer approximation
In quantum chemistry and molecular physics, the Born–Oppenheimer (BO) approximation is the assumption that the wave functions of atomic nuclei and electrons in a molecule can be treated separately, based on the fact that the nuclei are much heavier than the electrons. Due to the larger relative mass of a nucleus compared to an electron, the coordinates of the nuclei in a system are approximated as fixed, while the coordinates of the electrons are dynamic. The approach is named after Max Born and his 23-year-old graduate student J. Robert Oppenheimer, the latter of whom proposed it in 1927 during a period of intense foment in the development of quantum mechanics.
The approximation is widely used in quantum chemistry to speed up the computation of molecular wavefunctions and other properties for large molecules. There are cases where the assumption of separable motion no longer holds, which make the approximation lose validity (it is said to "break down"), but even then the approximation is usually used as a starting point for more refined methods.