Adsorption of Hexacyclic C6H6, C6H8, C6H10
and C6H12 on a Mo-terminated α-Mo2C (0001)
Surface
Xingchen Liu1, Alexander Tkalych1, Baojing Zhou1.2 Andreas M. Köster3 and Dennis
R. Salahub1*
1
Department of Chemistry and ISEEE – Institute for Sustainable Energy,
Environment and Economy, University of Calgary, 2500 University Drive NW,
Calgary, Alberta, Canada T2N 1N4
2
Computational Institute for Molecules and Materials, Department of Chemistry,
Nanjing University of Science and Technology, Nanjing 210094, China
3
Departamento de Química, Cinvestav, Avenida. Instituto Politécnico Nacional 2508,
A.P. 14-740, Mexico City, Mexico
Supporting Information
Auxiliary density and Kohn-Shan density
The accuracy of the auxiliary density fitting was confirmed by the comparison of
adsorption energies and structures of the clusters below, using the most favorable
adsorbate/configuration as representatives. To evaluate the structural change of the
binding between the adsorbates and the cluster, the shortest distances of a carbon
atom from the adsorbate to a molybdenum atom of the cluster were compared. The
S1
deviations are within 0.01-0.03 Å. The energetic comparison was made by comparing
the adsorption energies, with dispersion correction included. Most of the adsorption
energy changes are within 0.1 eV, with a few exceptions. The trends, however, are
maintained. Considering that auxiliary density fitting calculations are about 5 times
faster than Kohn-Sham density calculations, the accuracy of the former is fairly good
for studying the interaction of small molecules with large clusters. The BSSE
calculations with Auxiliary density functions, however, failed to reproduce the
Kohn-Sham density calculations. Therefore, the auxiliary function density can be used
to speed up the Kohn-Sham density calculations on the current systems in terms of
structures and adsorption energies, but the BSSE calculations must be performed with
the Kohn-Sham density approach.
Table 1. Comparison of the structure and adsorption energy (with dispersion
correction) between Kohn-Sham density (basis) and Auxiliary density (auxis).
Adsorbate
Shortest dC-Mo (Å)
Ead (eV)
BSSE (eV)
Basis
Auxis
Basis
Auxis
Basis
Auxis
C6H6-Vc
2.16
2.17
-3.19
-3.17
0.19
1.85
C6H6-Hm
2.12
2.12
-2.98
-2.35
0.43
2.06
C6H6-Hc
2.16
2.18
-2.89
-2.52
0.30
2.04
12C6H8
2.12
2.13
-3.33
-3.24
0.45
1.82
13C6H8
2.26
2.27
-5.15
-5.26
0.55
1.72
14C6H8
2.19
2.20
-3.20
-3.03
0.66
1.63
1234C6H10
2.20
2.23
-1.93
-2.04
0.39
1.61
1235C6H10
2.30
2.28
-4.42
-4.65
0.85
1.68
S2
1245C6H10
2.28
2.31
-3.08
-3.10
0.44
1.31
C6H12
2.72
2.73
-0.77
-0.90
0.37
1.21
S3