TY - JOUR
T1 - The structure and energetics of the HCN → HNC transition state
AU - Lee, Timothy J.
AU - Rendell, Alistair P.
PY - 1991/3/8
Y1 - 1991/3/8
N2 - The optimum geometries and quadratic force constants of HCN, HNC and the transition state connecting them have been determined at the single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory. Energy differences were evaluated using the CCSD and CCSD(T) methods in conjunction with large atomic natural orbital basis sets containing g-type basis functions on the heavy atoms and f-type functions on hydrogen. The most reliable structure obtained for the transition state has bond distances of 1.194, 1.188 and 1.389 Å for rCN, rCH and rNH, respectively. Including a correction for zero-point vibrational energies, the transition state is predicted to be 44.6 ± 1.0 kcal/mol above the HCN isomer, while HNC is predicted to be 14.4 ± 1.0 kcal/mol above HCN. The latter value is in excellent agreement with the most recent experimental determination (14.8 ± 2.0 kcal/mol).
AB - The optimum geometries and quadratic force constants of HCN, HNC and the transition state connecting them have been determined at the single and double excitation coupled-cluster (CCSD) and CCSD(T) levels of theory. Energy differences were evaluated using the CCSD and CCSD(T) methods in conjunction with large atomic natural orbital basis sets containing g-type basis functions on the heavy atoms and f-type functions on hydrogen. The most reliable structure obtained for the transition state has bond distances of 1.194, 1.188 and 1.389 Å for rCN, rCH and rNH, respectively. Including a correction for zero-point vibrational energies, the transition state is predicted to be 44.6 ± 1.0 kcal/mol above the HCN isomer, while HNC is predicted to be 14.4 ± 1.0 kcal/mol above HCN. The latter value is in excellent agreement with the most recent experimental determination (14.8 ± 2.0 kcal/mol).
UR - http://www.scopus.com/inward/record.url?scp=0000829961&partnerID=8YFLogxK
U2 - 10.1016/0009-2614(91)90073-I
DO - 10.1016/0009-2614(91)90073-I
M3 - Article
AN - SCOPUS:0000829961
VL - 177
SP - 491
EP - 497
JO - Chemical Physics Letters
JF - Chemical Physics Letters
SN - 0009-2614
IS - 6
ER -