The vibrational modes of CO adsorbed on Pt(111) in the c(4×2) structure have been studied within the harmonic approximation, using density functional calculations. The characters, fundamental energies, and dipole activities have been determined for all modes. For top-adsorbed molecules, the static adsorbate–adsorbate interaction is found to induce energy splitting among frustrated lateral translational modes, which have previously been assumed to be degenerate, and a reassignment of previously measured vibrational energies to low-energy modes is proposed. For bridge-adsorbed molecules, the frustrated rotational fundamental transitions, which should be dipole forbidden from the local adsorption site symmetry, are found to be weakly dipole active.

1.
H.
Steininger
,
S.
Lehwald
, and
H.
Ibach
,
Surf. Sci.
123
,
264
(
1982
).
2.
E.
Schweizer
,
B. N. J.
Persson
,
M.
Tühaus
,
D.
Hoge
, and
A. M.
Bradshaw
,
Surf. Sci.
213
,
49
(
1989
).
3.
A. P.
Graham
and
J. P.
Toennies
,
Surf. Sci.
427–428
,
1
(
1999
).
4.
D.
Hoge
,
M.
Tühaus
,
E.
Schweizer
, and
A. M.
Bradshaw
,
Chem. Phys. Lett.
151
,
230
(
1988
).
5.
U.
Engström
and
R.
Ryberg
,
Phys. Rev. Lett.
78
,
1944
(
1997
).
6.
U. Engström, Ph.D. thesis, Chalmers University of Technology, 1999.
7.
A. M.
Lahee
,
J. P.
Toennies
, and
Ch.
Wöll
,
Surf. Sci.
177
,
371
(
1986
).
8.
A. P.
Graham
,
J. Chem. Phys.
109
,
9583
(
1998
).
9.
P.
Uvdal
,
P.-A.
Karlsson
,
C.
Nyberg
,
S.
Andersson
, and
N. V.
Richardson
,
Surf. Sci.
202
,
167
(
1988
).
10.
J. A.
Leiro
and
M.
Persson
,
Surf. Sci.
207
,
473
(
1989
).
11.
DACAPO-1.30 of B. Hammer et al., CAMP, DTH, Lyngby, Denmark.
12.
J. P.
Perdew
,
J. A.
Chevary
,
S. H.
Vosko
,
K. A.
Jackson
,
M. R.
Pederson
,
D. J.
Singh
, and
C.
Fiolhais
,
Phys. Rev. B
46
,
6671
(
1992
).
13.
L.
Bengtsson
,
Phys. Rev. B
59
,
12301
(
1999
).
14.
D. F.
Ogletree
,
M. A.
van Hove
, and
G. A.
Somorjai
,
Surf. Sci.
173
,
351
(
1986
).
15.
Y.
Morikawa
,
J. J.
Mortensen
,
B.
Hammer
, and
J. K.
No/rskov
,
Surf. Sci.
386
,
67
(
1997
).
16.
N. V.
Richardson
and
A. M.
Bradshaw
,
Surf. Sci.
88
,
255
(
1979
).
17.
U.
Engström
and
R.
Ryberg
,
J. Chem. Phys.
112
,
1959
(
2000
).
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