Via simulation, the self-diffusion mechanism in liquid argon just above the melting point was analysed over a very short time-scale. The essential mechanism was divided into two parts. One was jumping of an atom passing through its surrounding atom-cage, in which the jump frequency was about 1.25% per 100 oscillations of the central atom. This contributed about 20% to the total self-diffusion coefficient. The other process was Brownian-like movement of an atom and its cage (having an effective mass of 12.2 argons) as a whole.

Intuitive Interpretation of Self-Diffusion Mechanism in Liquid Argon by Molecular Dynamics. Furukawa, K., Tanaka, M.: Electrochemical Society Extended Abstracts, 1985, 85[2], 698-9. See also: Proceedings - The Electrochemical Society, 1986, 86[1], 71-80

 

Table 31

Arrhenius parameters for diffusion on Ar(111)

 

Coverage (adatoms)

Reduced Temperature

Species

E (cal/mol)

D0 (cm2/s)

1

<0.66

Kr

7.0 x 10-7

109

1

0.66-0.83

Kr

6.7 x 103

2575

1

<0.66

Ar

1.3 x 10-6

116

1

0.66-0.83

Ar

1.7 x 103

2337

20

<0.66

Kr

3.1 x 10-5

255

20

0.66-0.80

Kr

7.6 x 10-2

1101

20

<0.62

Ar

5.7 x 10-5

272

20

0.62-0.83

Ar

1.3 x 10-2

809