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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 ...
The van der Waals forces [4] are usually described as a combination of the London dispersion forces between "instantaneously induced dipoles", [5] Debye forces between permanent dipoles and induced dipoles, and the Keesom force between permanent molecular dipoles whose rotational orientations are dynamically averaged over time.
DLVO theory is the combined effect of van der Waals and double layer force. For the derivation, different conditions must be taken into account and different equations can be obtained. [ 13 ] But some useful assumptions can effectively simplify the process, which are suitable for ordinary conditions.
However, it also has some features of covalent bonding: it is directional, stronger than a van der Waals force interaction, produces interatomic distances shorter than the sum of their van der Waals radii, and usually involves a limited number of interaction partners, which can be interpreted as a kind of valence. The number of Hydrogen bonds ...
Non-covalent interactions can be classified into different categories, such as electrostatic, π-effects, van der Waals forces, and hydrophobic effects. [3] [2] Non-covalent interactions [4] are critical in maintaining the three-dimensional structure of large molecules, such as proteins and nucleic acids.
Dispersion stabilization is often signified by atomic contacts below their van der Waals radii in a molecule's crystal structure. Especially for H•••H contacts between bulky, rigid, polarizable groups, short contacts may indicate that a dispersion force is overcoming the Pauli repulsion present between the two H atoms.
The London dispersion force is a component of the van der Waals force, which is itself a sum of many forces. We note in the former article that "dispersion forces are usually dominant of the three van der Waals forces", with the other two being orientation and induction forces.
The Van der Waals forces are effective only up to several hundred angstroms. When the interactions are too far apart, the dispersion potential decays faster than /; this is called the retarded regime, and the result is a Casimir–Polder force.