Potential energy surfaces for the Pt sub 2 +H sub 2 reaction
- Department of Chemistry, Arizona State University, Tempe, Arizona 85287-1604 (US)
Potential energy surfaces for the Pt{sub 2}+H{sub 2} reaction are obtained using a complete active space multiconfiguration self-consistent field (CAS-MCSCF) method followed by multireference singles+double CI (MRSDCI) calculations. Several approaches of H{sub 2} such as parallel, perpendicular, collinear, end-on with respect to Pt{sub 2} are considered. In addition, out-of-plane twist motions of hydrogens relative to the Pt--Pt bond are considered. The parallel approach was found to be most reactive in the {sup 1}{ital A}{sub 1} electronic state, which forms a {ital cis} Pt{sub 2}H{sub 2} saddle point after surmounting a barrier of {similar to}20 kcal/mol. The saddle point thus formed spontaneously transforms to a {ital trans} Pt{sub 2}H{sub 2}, {sup 1}{ital A}{sub {ital g}} ground state through an out-of-plane twist motion. The dissociation of H{sub 2} in the parallel mode of collision was found to be brought about primarily through the interaction of the {ital d}({delta}) orbitals of the two Pt atoms with the H{sub 2} 1{sigma}{sub {ital g}} and 1{sigma}{sup *}{sub {ital u}} orbitals. The spin--orbit effects were studied using a relativistic CI (RCI) method and found to be significant for Pt{sub 2}H{sub 2}. Spin--orbit coupling was found to induce an avoided crossing. This destabilizes the Pt{sub 2}H{sub 2}({sup 1}{ital A}{sub {ital g}}) molecular state with respect to the dissociated Pt{sub 2}+H{sub 2}. The energy separation between the Pt{sub 2}H{sub 2} {sup 1}{ital A}{sub {ital g}} {ital trans} minimum and the {ital cis} saddle point was calculated at the MRSDCI level as 3 kcal/mol. We find that the reactivity of Pt{sub 2} with H{sub 2} varies as a function of electronic state and orientation.
- OSTI ID:
- 6256073
- Journal Information:
- Journal of Chemical Physics; (USA), Vol. 94:2; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
Similar Records
Potential energy surfaces for the insertion of Ta and Ta sup + into H sub 2
Laser vaporization/rare gas matrix-isolation electron spin resonance studies of PdH sup + sub 2 , PdD sup + sub 2 , PdH, and PdD: Theoretical investigation of PdH sup + sub 2
Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDROGEN
CHEMICAL REACTION KINETICS
PLATINUM
CONFIGURATION INTERACTION
DIMERS
ELECTRONIC STRUCTURE
ORIENTATION
POTENTIAL ENERGY
REACTIVITY
SELF-CONSISTENT FIELD
ELEMENTS
ENERGY
KINETICS
METALS
NONMETALS
PLATINUM METALS
REACTION KINETICS
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties