The polarizable continuum model (PCM) is a commonly used method in

computational chemistry Computational chemistry is a branch of chemistry that uses computer simulation to assist in solving chemical problems. It uses methods of theoretical chemistry, incorporated into computer programs, to calculate the structures and properties of mo ...

to model

solvation Solvation (or dissolution) describes the interaction of a solvent with dissolved molecules. Both ionized and uncharged molecules interact strongly with a solvent, and the strength and nature of this interaction influence many properties of the ...

effects. If it is necessary to consider each solvent molecule as a separate molecule, the computational cost of modeling a solvent-mediated

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...

would grow prohibitively high. Modeling the solvent as a polarizable continuum, rather than individual molecules, makes ''

ab initio ''Ab initio'' ( ) is a Latin term meaning "from the beginning" and is derived from the Latin ''ab'' ("from") + ''initio'', ablative singular of ''initium'' ("beginning"). Etymology Circa 1600, from Latin, literally "from the beginning", from a ...

'' computation feasible. Two types of PCMs have been popularly used: the dielectric PCM (D-PCM) in which the continuum is polarizable (see

dielectrics In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field. When a dielectric material is placed in an electric field, electric charges do not flow through the mat ...

) and the conductor-like PCM (C-PCM) in which the continuum is conductor-like similar to COSMO Solvation Model.Jacopo Tomasi, Benedetta Mennucci, and Roberto Cammi (2005). "Quantum Mechanical Continuum Solvation Models."

Chem. Rev. ''Chemical Reviews'' is peer-reviewed scientific journal published twice per month by the American Chemical Society. It publishes review articles on all aspects of chemistry. It was established in 1924 by William Albert Noyes (University of Illino ...

105(8): 2999-309

/ref> The molecular Gibbs free energy, free energy of solvation is computed as the sum of three terms: :''G''_sol = ''G''_es + ''G''_dr + ''G''_cav ::''G''_es = electrostatic ::''G''_dr = dispersion-repulsion ::''G''_cav = cavitation The Charge-transfer effect is also considered as a part of solvation in cases. The PCM solvation model is available for calculating energies and gradients at the Hartree–Fock and

density functional theory Density-functional theory (DFT) is a computational quantum mechanical modelling method used in physics, chemistry and materials science to investigate the electronic structure (or nuclear structure) (principally the ground state) of many-bo ...

(DFT) levels in several quantum chemical computational packages such as

Gaussian Carl Friedrich Gauss (1777–1855) is the eponym of all of the topics listed below. There are over 100 topics all named after this German mathematician and scientist, all in the fields of mathematics, physics, and astronomy. The English eponymo ...

GAMESS GAMESS is a computational chemistry software program and stands for General Atomic and Molecular Electronic Structure System. The original Quantum Chemistry Program Exchange (QCPE) code of GAMESS split in 1981 and now the three version differ consid ...

an
JDFTx
The authors of a 2002 paper observe that PCM has limitations where non-electrostatic effects dominate the solute-solvent interactions. They write in the abstract: "Since only electrostatic solute-solvent interactions are included in the PCM, our results lead to the conclusion that, for the seven molecules studied, in

cyclohexane Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colorless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohex ...

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscible wi ...

, methanol, and acetonitrile electrostatic effects are dominant while in

carbon tetrachloride Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemi ...

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen ato ...

, and

chloroform Chloroform, or trichloromethane, is an organic compound with formula C H Cl3 and a common organic solvent. It is a colorless, strong-smelling, dense liquid produced on a large scale as a precursor to PTFE. It is also a precursor to various re ...

other nonelectrostatic effects are more important." There is an integral equation formalism (IEF) version of the PCM which is very commonly used. PCM is also used to model outer solvation layers in multi-layered solvation approach.Mark S. Gordon "CLUSTER-BASED APPROACHES TO SOLVATION" Iowa State University, Ames Laborator

References

{{reflist Computational chemistry

See also

References