TY  - JOUR
A1  - Sinha, Shreya
A1  - Saalfrank, Peter
T1  - "Inverted" CO molecules on NaCl(100)
T2  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Somewhat surprisingly, inverted ("O-down") CO adsorbates on NaCl(100) were recently observed experimentally after infrared vibrational excitation (Lau et al., Science, 2020, 367, 175-178). Here we characterize these species using periodic density functional theory and a quantum mechanical description of vibrations. We determine stationary points and minimum energy paths for CO inversion, for low (1/8 and 1/4 monolayers (ML)) and high (1 ML) coverages. Transition state theory is applied to estimate thermal rates for "C-down" to "O-down" isomerization and the reverse process. For the 1/4 ML p(1 x 1) structure, two-dimensional and three-dimensional potential energy surfaces and corresponding anharmonic vibrational eigenstates obtained from the time-independent nuclear Schrodinger equation are presented. We find (i) rather coverage-independent CO inversion energies (of about 0.08 eV or 8 kJ mol(-1) per CO) and corresponding classical activation energies for "C-down" to "O-down" isomerization (of about 0.15 eV or 14 kJ mol(-1) per CO); (ii) thermal isomerization rates at 22 K which are vanishingly small for the "C-down" to "O-down" isomerization but non-negligible for the back reaction; (iii) several "accidentally degenerate" pairs of eigenstates well below the barrier, each pair describing "C-down" to "O-down" localized states.
Y1  - 2020
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/57190
SN  - 1463-9076
SN  - 1463-9084
VL  - 23
IS  - 13
SP  - 7860
EP  - 7874
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -