# Effects of van der Waals interactions on the polarizability of atoms, oscillators, and dipolar rotors at long range

## Abstract

Both classical multipolar interactions and the interaction-induced changes in intrinsic polarizability associated with van der Waals forces contribute to the long-range pair polarizability of atoms, oscillators, and dipolar rotors. The frequency-dependent nonlinear polarization of an isotropic system by the field due to the randomly fluctuating multipoles of neighboring systems and by an applied field determines the change in intrinsic polarizability induced in the system by van der Waals interactions. Frequency-dependent values for the mean-square fluctuating multipoles are obtained from the fluctuation--dissipation theorem. To lowest order (R/sup -6/) the dispersion contribution to the polarizability ..cap alpha..(..omega..) of a pair of atoms A and B is related to an integral over imaginary frequencies iu of the symmetrized product (1+P/sub AB/)..gamma../sup A/(..omega.., iu,-iu)..cap alpha../sup B/(iu), where ..gamma../sup A/(..omega.., iu,-iu) is a linear combination of the ..gamma..-hyperpolarizability tensor components of atom A and ..cap alpha../sup B/(iu) is the polarizability of atom B. By using a mean-frequency approximation, the dispersion contribution to the static polarizability of inert-gas atom pairs is found in terms of the known van der Waals coefficients C/sup A//sub 6//sup B/, the static atomic polarizabilities, and static ..gamma.. hyperpolarizabilities. To order R/sup -6/, the change in intrinsic polarizability is positive for hydrogenmore »

- Authors:

- Publication Date:

- Research Org.:
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824

- OSTI Identifier:
- 6213968

- Resource Type:
- Journal Article

- Journal Name:
- J. Chem. Phys.; (United States)

- Additional Journal Information:
- Journal Volume: 75:6

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 74 ATOMIC AND MOLECULAR PHYSICS; ATOM COLLISIONS; POLARIZABILITY; VAN DER WAALS FORCES; MOLECULE COLLISIONS; FREQUENCY DEPENDENCE; COLLISIONS; ELECTRICAL PROPERTIES; PHYSICAL PROPERTIES; 640304* - Atomic, Molecular & Chemical Physics- Collision Phenomena

### Citation Formats

```
Hunt, K L.C., Zilles, B A, and Bohr, J E.
```*Effects of van der Waals interactions on the polarizability of atoms, oscillators, and dipolar rotors at long range*. United States: N. p., 1981.
Web. doi:10.1063/1.442404.

```
Hunt, K L.C., Zilles, B A, & Bohr, J E.
```*Effects of van der Waals interactions on the polarizability of atoms, oscillators, and dipolar rotors at long range*. United States. doi:10.1063/1.442404.

```
Hunt, K L.C., Zilles, B A, and Bohr, J E. Tue .
"Effects of van der Waals interactions on the polarizability of atoms, oscillators, and dipolar rotors at long range". United States. doi:10.1063/1.442404.
```

```
@article{osti_6213968,
```

title = {Effects of van der Waals interactions on the polarizability of atoms, oscillators, and dipolar rotors at long range},

author = {Hunt, K L.C. and Zilles, B A and Bohr, J E},

abstractNote = {Both classical multipolar interactions and the interaction-induced changes in intrinsic polarizability associated with van der Waals forces contribute to the long-range pair polarizability of atoms, oscillators, and dipolar rotors. The frequency-dependent nonlinear polarization of an isotropic system by the field due to the randomly fluctuating multipoles of neighboring systems and by an applied field determines the change in intrinsic polarizability induced in the system by van der Waals interactions. Frequency-dependent values for the mean-square fluctuating multipoles are obtained from the fluctuation--dissipation theorem. To lowest order (R/sup -6/) the dispersion contribution to the polarizability ..cap alpha..(..omega..) of a pair of atoms A and B is related to an integral over imaginary frequencies iu of the symmetrized product (1+P/sub AB/)..gamma../sup A/(..omega.., iu,-iu)..cap alpha../sup B/(iu), where ..gamma../sup A/(..omega.., iu,-iu) is a linear combination of the ..gamma..-hyperpolarizability tensor components of atom A and ..cap alpha../sup B/(iu) is the polarizability of atom B. By using a mean-frequency approximation, the dispersion contribution to the static polarizability of inert-gas atom pairs is found in terms of the known van der Waals coefficients C/sup A//sub 6//sup B/, the static atomic polarizabilities, and static ..gamma.. hyperpolarizabilities. To order R/sup -6/, the change in intrinsic polarizability is positive for hydrogen and inert-gas atom pairs, zero for pairs of isotropic Drude-model oscillators with vanishing dipole at the equilibrium geometry, and negative for pairs of rigid dipolar rotors.},

doi = {10.1063/1.442404},

journal = {J. Chem. Phys.; (United States)},

number = ,

volume = 75:6,

place = {United States},

year = {1981},

month = {9}

}