We use classical molecular dynamics simulations to investigate temperature control of unsupported clusters using a noble gas atmosphere. The simulations are performed using a many-body interaction scheme for the intra-cluster potential, while a pairwise Lennard-Jones potential is used to model the interaction between the noble gas and the clusters. In order to isolate different parameters determining the energy exchange efficiency, we have studied the energy transfer with respect to (i) impact parameter, (ii) cluster temperature, (iii) noble gas temperature, (iv) gas–metal interaction strength, (v) metal potential, and (vi) noble gas mass. With these results, we are able to estimate the number of collisions needed to equilibrate a cluster at a given gas temperature. Our estimates are confirmed by simulations of cluster cooling in a noble gas atmosphere.

1.
K. E.
Schriver
,
J. L.
Persson
,
E. C.
Honea
, and
R. L.
Whetten
,
Phys. Rev. Lett.
64
,
2539
(
1990
).
2.
W. A.
de Heer
,
P.
Milani
, and
A.
Chatelain
,
Phys. Rev. Lett.
65
,
488
(
1990
).
3.
L. Holmgren and A. Rosén (unpublished).
4.
T. G.
Dietz
,
M. A.
Duncan
,
D. E.
Powers
, and
R. E.
Smalley
,
J. Chem. Phys.
86
,
3911
(
1981
).
5.
H. Haberland, Clusters of Atoms and Molecules, edited by H. Haberland (Springer-Verlag, Berlin, 1994).
6.
P.
Milani
and
W. A.
de Heer
,
Phys. Rev. B
44
,
8346
(
1991
).
7.
M. Y.
Hahn
and
R. L.
Whetten
,
Phys. Rev. Lett.
61
,
1190
(
1988
).
8.
D.
Tománek
,
S.
Mukherjee
, and
K. H.
Bennemann
,
Phys. Rev. B
28
,
665
(
1983
);
D.
Tománek
,
S.
Mukherjee
, and
K. H.
Bennemann
,
29
,
1076
(E) (
1984
).,
Phys. Rev. B
9.
W.
Zhong
,
Y. S.
Li
, and
D.
Tománek
,
Phys. Rev. B
44
,
13
053
(
1991
).
10.
B. H.
Mahan
,
J. Chem. Phys.
10
,
5221
(
1970
).
11.
C. N.
Hinselwood
,
Proc. R. Soc. London Ser. A
,
113
,
230
(
1927
).
12.
E. K.
Grimmelmann
,
J. C.
Tully
, and
M. J.
Cardillo
,
J. Chem. Phys.
72
,
1039
(
1980
).
13.
H.
Grönbeck
,
D.
Tománek
,
S. G.
Kim
, and
A.
Rosén
,
Chem. Phys. Lett.
264
,
39
(
1997
).
14.
See, e.g.,
I.
Oref
and
D. C.
Tardy
,
Chem. Rev.
90
,
1407
(
1990
).
15.
L.
Ming
,
J.
Davidsson
, and
S.
Nordholm
,
Chem. Phys.
201
,
121
(
1995
).
16.
J.
Schulte
,
R. R.
Lucchese
, and
W. H.
Marlow
,
J. Chem. Phys.
99
,
1178
(
1993
).
17.
P.
de Sainte Claire
and
W. L.
Hase
,
J. Phys. Chem.
100
,
8190
(
1996
);
P.
de Sainte Claire
,
G. H.
Peslherbe
, and
W. L.
Hase
,
J. Phys. Chem.
99
,
8147
(
1995
).,
J. Phys. Chem.
18.
J.
Schulte
and
G.
Seifert
,
Chem. Phys. Lett.
221
,
230
(
1994
).
19.
W.
Zhong
,
Y.
Cai
, and
D.
Tománek
,
Phys. Rev. B
46
,
8099
(
1992
);
W.
Zhong
,
Y.
Cai
, and
D.
Tománek
,
Nature
362
,
435
(
1993
).
20.
G. L.
Estiú
and
M. C.
Zerner
,
J. Phys. Chem.
98
,
4793
(
1994
).
21.
The potential parameters for sodium are ξ0 = 0.5176 eV,ε0 = 0.05350 eV,p = 9, q = 3, and r0 =thinsp3.66 Å.
22.
Numerical Recipes, edited by W. H. Press, S. A. Teukolsky, W. T. Vetterling, and B. P. Flannery (Cambridge University Press, Cambridge, 1992).
23.
D. G.
Leopold
,
J.
Ho
, and
W. C.
Lineberger
,
J. Chem. Phys.
86
,
1715
(
1987
).
24.
The energy expression for energy exchange in hard sphere collisions is ΔE = 1+{4(1−(b/D)2)/[m/M+1]}[1/(m/M+1)−1]. Here, b is the impact parameter, D is the sum of the hard sphere radii for the cluster and the atom. m and M are the masses for the atom and the cluster, respectively.
25.
J. Westergren, H. Grönbeck, S. G. Kim, and D. Tománek (unpublished).
26.
S.
Nosé
,
J. Chem. Phys.
81
,
511
(
1984
);
W. G.
Hoover
,
Phys. Rev. A
31
,
1695
(
1985
).
27.
We checked this assumption in the case of helium collisions with Pd13. An average of kpot in Fig. 7 is 2.0 μeV/K, which could be compared with the value of ktot which is 4.3 μeV/K.
28.
R. S.
Berry
,
J.
Jellinek
, and
G.
Natanson
,
Phys. Rev. B
30
,
919
(
1984
);
T. L.
Beck
,
J.
Jellinek
, and
R. S.
Berry
,
J. Chem. Phys.
87
,
545
(
1987
).
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