Tip

All input files can be downloaded: Files.

pcm

This option controls the polarized continuum model.

Options

model

Value

IEFPCM. Will use IEF-PCM (integral equation formalism of PCM) model.

CPCM. Will use C-PCM (Conductor-like PCM) model.

COSMO. Will use COSMO (conductor-like screening model) model.

Default

IEFPCM

The PCM model. IEFPCM is recommended.

solvent

Value

7 real numbers

water

acetic acid

acetone

acetonitrile

acetophenone

aniline

anisole

benzaldehyde

benzene

benzonitrile

benzyl chloride

1-bromo-2-methylpropane

bromobenzene

bromoethane

bromoform

1-bromooctane

1-bromopentane

2-bromopropane

1-bromopropane

butanal

butanoic acid

1-butanol

2-butanol

butanone

butanonitrile

butyl acetate

butylamine

n-butylbenzene

sec-butylbenzene

tert-butylbenzene

carbon disulfide

carbon tetrachloride

chlorobenzene

sec-butyl chloride

chloroform

1-chlorohexane

1-chloropentane

1-chloropropane

o-chlorotoluene

m-cresol

o-cresol

cyclohexane

cyclohexanone

cyclopentane

cyclopentanol

cyclopentanone

cis-decalin

trans-decalin

decalin (cis/trans mixture)

n-decane

1-decanol

1,2-dibromoethane

dibromomethane

dibutyl ether

o-dichlorobenzene

1,2-dichloroethane

cis-dichloroethylene

trans-dichloroethylene

dichloromethane

diethyl ether

diethyl sulfide

diethylamine

diiodomethane

diisopropyl ether

dimethyl disulfide

dimethyl sulfoxide

n,n-dimethylacetamide

cis-1,2-dimethylcyclohexane

n,n-dimethylformamide

2,4-dimethylpentane

2,4-dimethylpyridine

2,6-dimethylpyridine

1,4-dioxane

diphenyl ether

dipropylamine

n-dodecane

1,2-ethanediol

ethanethiol

ethanol

ethyl acetate

ethyl formate

ethylbenzene

ethylphenyl ether

fluorobenzene

1-fluorooctane

formamide

formic acid

n-heptane

1-heptanol

2-heptanone

4-heptanone

n-hexadecane

n-hexane

hexanoic acid

1-hexanol

2-hexanone

1-hexene

1-hexyne

iodobenzene

1-iodobutane

iodoethane

1-iodohexadecane

iodomethane

1-iodopentane

1-iodopropane

isopropylbenzene

p-isopropyltoluene

mesitylene

methanol

2-methoxyethanol

methyl acetate

methyl benzoate

methyl butanoate

methyl formate

4-methyl-2-pentanone

methyl propanoate

2-methyl-1-propanol

2-methyl-2-propanol

n-methylaniline

methylcyclohexane

n-methylformamide (e/z mixture)

2-methylpentane

2-methylpyridine

3-methylpyridine

4-methylpyridine

nitrobenzene

nitroethane

nitromethane

1-nitropropane

2-nitropropane

o-nitrotoluene

n-nonane

1-nonanol

5-nonanone

n-octane

1-octanol

2-octanone

n-pentadecane

pentanal

n-pentane

pentanoic acid

1-pentanol

2-pentanone

3-pentanone

1-pentene

e-2-pentene

pentyl acetate

pentylamine

perfluorobenzene

phenylmethanol

propanal

propanoic acid

1-propanol

2-propanol

propanonitrile

2-propen-1-ol

propyl acetate

propylamine

pyridine

tetrachloroethene

tetrahydrofuran

tetrahydrothiophene-s,s-dioxide

tetralin

thiophene

thiophenol

toluene

tributyl phosphate

1,1,1-trichloroethane

1,1,2-trichloroethane

trichloroethene

triethylamine

2,2,2-trifluoroethanol

1,2,4-trimethylbenzene

2,2,4-trimethylpentane

n-undecane

m-xylene

o-xylene

p-xylene

xylene (mixture)

1,1-dichloroethane

1-iodopentene

1-pentyne

2-chlorobutane

benzyl alcohol

Default

None

The solvent name. It can be one of the string given in the table above, or 7 real numbers, which are: dielectric_constant refraction_index Abraham_alpha Abraham_beta abomaticity halogenicity macro_surface_tension.

If some properties are unknown, you can set them to 0.

radius

Value

UFF. Will use UFF atomic radii for tesselation.

Bondi. Will use UFF atomic radii for tesselation.

Default

UFF

This determines the radius type used for tesselation. UFF is highly recommended, since Bondi radii data is not complete for some common elements, like Fe.

tss_method

Value

Swig. Will use Swig algorithm for tesselation.

Switching. Will use Switching algorithm for tesselation.

Sphere. Will use sphere algorithm for tesselation.

Default

Swig

The algorithm for tesselation. Swig is recommended. Sphere is useful in the study of electron transfer.

grid_accuracy

Value

An integer

6, 14, 26, 38, 50, 86, 110

146, 170, 194, 302, 350, 434, 590

770, 974, 1202, 1454, 1730, 2030, 2354

2702, 3074, 3470, 3890, 4334, 4802, 5294

Default

302

The number of Lebedev points generated for tesselation. Usually 302 is enough. For higher accuracy, ``590``can be used.

Theoretical Background

The Polarizable Continuum Model (PCM) is a widely used implicit solvation model in computational chemistry. In PCM, the solute molecule is placed inside a cavity embedded in a continuous dielectric medium that represents the solvent. Instead of explicitly simulating individual solvent molecules, PCM treats the solvent as a polarizable continuum characterized by its dielectric constant and other macroscopic properties.

The interaction between the solute and the solvent is described by the polarization of the continuum in response to the solute’s charge distribution. This polarization, in turn, affects the electronic structure of the solute. PCM enables the calculation of solvation effects on molecular properties, such as energies, geometries, and spectra, with relatively low computational cost compared to explicit solvent models.

PCM is particularly useful for studying systems in solution, where solvent effects play a significant role in chemical reactivity, stability, and spectroscopic behavior. The model can be combined with various quantum chemical methods, such as Hartree-Fock and Density Functional Theory, to provide a more realistic description of molecules in their solvated environment.

Input Examples

Example: Use Built-in and Self-defined Solvent for CH3Cl with PCM

To use PCM in Qbics, we need to add the pcm keyword in the input file. There are two ways to use PCM:

  1. Use the built-in solvent list shown above.

  2. Explicitly give 7 numbers: dielectric_constant, refraction_index, Abraham_alpha, Abraham_beta, abomaticity, halogenicity, and macro_surface_tension. If some properties are unknown, you can set them to 0, but “dielectric_constant” must be at least given.

In the following, in pcm-1a.inp, we use aniline as solvent; in pcm-1b.inp, we explicitly give the dielectric constant, refraction index, Abraham alpha, Abraham beta, abomaticity, and halogenicity:

pcm-1a.inp
 1basis
 2    cc-pvdz
 3end
 4
 5pcm
 6     solvent aniline # Use aniline as solvent.
 7end
 8
 9mol
10  C                 -0.43654823    1.13197968    0.00000000
11  H                 -0.07987539    1.63637787    0.87365150
12  H                 -0.07987539    1.63637787   -0.87365150
13  H                 -1.50654823    1.13199286    0.00000000
14 Cl                  0.15009830   -0.52737135    0.00000000
15end
16
17task
18     energy b3lyp
19end

In the output file pcm-1a.out and pcm-1b.out, you will find the solvent definitions and PCM energies:

pcm-1a.out
 1Polarized continuum model is applied.
 2 Solvent:                aniline
 3  Dielectric constant:   6.8882
 4  Refraction index:      1.5863
 5  Abraham alpha:         0.2600
 6  Abraham beta:          0.4100
 7  Abomaticity:           0.8570
 8  Halogenicity:          0.0000
 9  Macro surface tension: 60.6200
10 Tesselation:
11..omitted..
12SCF Energies
13============
14Kinetic energy:                             499.00382795 Hartree
15Electron-nuclear attraction energy:       -1290.65493694 Hartree
16Pseudopotential energy:                       0.00000000 Hartree
17Exchange-correlation energy:                -28.07548686 Hartree
18Electron Coulomb energy:                    274.37629685 Hartree
19Electron exchange energy:                    -6.76432588 Hartree
20Nuclear repulsion energy:                    51.98869889 Hartree
21PCM solvation energy:                        -0.00201126 Hartree
22Grimme dispersion energy:                     0.00000000 Hartree
23----------------------------------------------------------------
24SCF energy (E):                            -500.12793727 Hartree
25Virial quotien (V/T):                        -2.00225271

To use models other than IEF-PCM model, we need to add the model keyword in the input file:

pcm-1c.inp
 1basis
 2    cc-pvdz
 3end
 4
 5pcm
 6    model   cpcm    # You can use IEFPCM, CPCM, or COSMO model.
 7    solvent aniline # Use aniline as solvent.
 8end
 9
10mol
11  C                 -0.43654823    1.13197968    0.00000000
12  H                 -0.07987539    1.63637787    0.87365150
13  H                 -0.07987539    1.63637787   -0.87365150
14  H                 -1.50654823    1.13199286    0.00000000
15 Cl                  0.15009830   -0.52737135    0.00000000
16end
17
18task
19     energy b3lyp
20end

The resutl is:

pcm-1c.out
 1SCF Energies
 2============
 3Kinetic energy:                             499.00431927 Hartree
 4Electron-nuclear attraction energy:       -1290.65504950 Hartree
 5Pseudopotential energy:                       0.00000000 Hartree
 6Exchange-correlation energy:                -28.07554137 Hartree
 7Electron Coulomb energy:                    274.37599784 Hartree
 8Electron exchange energy:                    -6.76433296 Hartree
 9Nuclear repulsion energy:                    51.98869889 Hartree
10PCM solvation energy:                        -0.00212532 Hartree
11Grimme dispersion energy:                     0.00000000 Hartree
12----------------------------------------------------------------
13SCF energy (E):                            -500.12803318 Hartree
14Virial quotien (V/T):                        -2.00225191