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  2. Molecular vibration - Wikipedia

    en.wikipedia.org/wiki/Molecular_vibration

    A molecular vibration is a periodic motion of the atoms of a molecule relative to each other, such that the center of mass of the molecule remains unchanged. The typical vibrational frequencies range from less than 10 13 Hz to approximately 10 14 Hz, corresponding to wavenumbers of approximately 300 to 3000 cm −1 and wavelengths of approximately 30 to 3 μm.

  3. Use of force continuum - Wikipedia

    en.wikipedia.org/wiki/Use_of_force_continuum

    A use of force continuum is a standard that provides law enforcement officers and civilians with guidelines as to how much force may be used against a resisting subject in a given situation. In some ways, it is similar to the U.S. military 's escalation of force (EOF). The purpose of these models is to clarify, both for law enforcement officers ...

  4. Force field (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Force_field_(chemistry)

    Part of force field of ethane for the C-C stretching bond. 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.

  5. Physical chemistry - Wikipedia

    en.wikipedia.org/wiki/Physical_chemistry

    t. e. Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria. Physical chemistry, in contrast to chemical ...

  6. Molecular dynamics - Wikipedia

    en.wikipedia.org/wiki/Molecular_dynamics

    Forces are then applied to specific atoms at either a constant velocity or a constant force. Umbrella sampling is used to move the system along the desired reaction coordinate by varying, for example, the forces, distances, and angles manipulated in the simulation. Through umbrella sampling, all of the system's configurations—both high-energy ...

  7. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    Molecule. Atomic force microscopy (AFM) image of a PTCDA molecule, in which the five six-carbon rings are visible. [1] A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. [2] AFM image of 1,5,9-trioxo-13-azatriangulene and its chemical structure. [3]

  8. London dispersion force - Wikipedia

    en.wikipedia.org/wiki/London_dispersion_force

    London dispersion forces (LDF, also known as dispersion forces, London forces, instantaneous dipole–induced dipole forces, fluctuating induced dipole bonds[1] or loosely as van der Waals forces) are a type of intermolecular force acting between atoms and molecules that are normally electrically symmetric; that is, the electrons are ...

  9. Non-covalent interaction - Wikipedia

    en.wikipedia.org/wiki/Non-covalent_interaction

    In chemistry, a non-covalent interaction differs from a covalent bond in that it does not involve the sharing of electrons, [1] but rather involves more dispersed variations of electromagnetic interactions between molecules or within a molecule. The chemical energy released in the formation of non-covalent interactions is typically on the order ...