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Potential energy surfaces for RhCO from DFT calculations
Author(s) -
Biemolt W.,
Jansen A. P. J.
Publication year - 1994
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540151002
Subject(s) - rhodium , morse potential , chemistry , carbon monoxide , density functional theory , atomic physics , atom (system on chip) , potential energy , bent molecular geometry , center of mass (relativistic) , ground state , electronic structure , computational chemistry , physics , catalysis , quantum mechanics , biochemistry , organic chemistry , energy–momentum relation , computer science , embedded system
We present potential energy surfaces for RhCO obtained from density functional theory for two electronic states of RhCO. We have performed local spin‐density calculations including relativistic as well as gradient corrections. The construction of a reasonably accurate atom–atom potential for RhCO is not possible. We were much more successful in constructing the potential energy surfaces by representing the potential as a spherical expansion. The expansion coefficients, which are functions of the distance between the rhodium atom and the carbon monoxide center of mass, can be represented by Lennard‐Jones, Buckingham, or Morse functions, with an error of the fit within 10 kJ/mol. The potential energy surfaces, using Morse functions, predict that the electronic ground state of RhCO is 2 Σ + or 2 Δ. This is a linear structure with an equilibrium distance of rhodium to the carbon monoxide center of mass of 0.253 nm. The bonding energy is −184 kJ/mol. Further, Morse functions predict that the first exicted state is 4 A ′. This is a bent structure (∠RhCO = 14°) with an equilibrium distance of rhodium to the carbon monoxide center of mass of 0.298 nm. The bonding energy of this state is −60 kJ/mol. Both these predictions are in good agreement with the actual density functional calculations. We found 0.250 nm with −205 kJ/mol for 2 Σ + and 0.253 nm with −199 kJ/mol for 2 Δ. For 4 A ′, we found 0.271 nm, ∠RhCO = 30°, with −63 kJ/mol. The larger deviation for 4 A ′ than for 2 Σ + or 2 Δ is a consequence of the fact that the minimum for 4 A ′ is a very shallow well. © 1994 by John Wiley & Sons, Inc.