Anchoring the hydrogen sulfide dimer potential energy surface to juxtapose (H2S)2 with (H2O)2

Abstract

Twelve stationary points have been characterized on the (H2S)2 potential energy surface using the MP2 and CCSD(T) methods with large, correlation consistent basis sets. To the best of our knowledge, five of the structures have not been identified elsewhere and are presented here for the first time. A similar analysis was performed on the ten, well-known structures of the water dimer in order to facilitate direct comparisons between the corresponding (H2O)2 and (H2S)2 configurations. Harmonic vibrational frequency computations identify three (H2S)2 configurations as minima, four as transition states, and five as higher-order saddle points (ni = 0, ni = 1, and ni ≥ 2, respectively, where ni is the number of imaginary frequencies). The two local minima and four transition state structures identified have electronic energies within 0.73 kJ mol−1 of the global minimum near the CCSD(T) complete basis set (CBS) limit, and the five higher-order saddle points range from 1.90 kJ mol−1 to 4.31 kJ mol−1 above the global minimum at the same level of theory. One of the more substantial differences observed between the H2S and H2O systems is that (H2O)2 has only a single minimum, while the other nine stationary points are significantly higher in energy ranging from 2.15 kJ mol−1 to 14.89 kJ mol−1 above the global minimum near the CCSD(T) CBS limit. For (H2S)2, the electronic dissociation energy of the global minimum is only 7.02 kJ mol−1 at the CCSD(T) CBS limit, approximately three times smaller than the dissociation energy of (H2O)2.

Systematic analysis of electronic barrier heights and widths for concerted proton transfer in cyclic hydrogen bonded clusters: (HF)n, (HCl)n and (H2O)n where n = 3, 4, 5

“…cc-pVXZ for H and aug-cc-pVXZ for O, F and Cl, hereafter denoted haXZ). Estimates of the Hartree-Fock self-consistent field energy at the CBS limit (E CBS SCF ) was obtained using an algebraic expression 113 for the threeparameter exponential function proposed by Feller 114 with energies from 3 sequential basis sets (small (SZ), medium (MZ) and large (LZ), such as aTZ/aQZ/a5Z or haQZ/ha5Z/ha6Z).…”

“…Similarly, the electronic correlation energy at the CBS limit (E CBS c ) was calculated using an algebraic expression 113 for the two-parameter inverse cubic function described by Helgaker and co-workers 115 with two consecutive basis sets from either the aXZ or haXZ series (denoted here as sZ and lZ for the smaller and larger basis sets, respectively).…”

“…cc-pV X Z for H and aug-cc-pV X Z for O, F and Cl, hereafter denoted ha X Z). Estimates of the Hartree–Fock self-consistent field energy at the CBS limit ( E CBS SCF ) was obtained using an algebraic expression 113 for the three-parameter exponential function proposed by Feller 114 with energies from 3 sequential basis sets (small (SZ), medium (MZ) and large (LZ), such as aTZ/aQZ/a5Z or haQZ/ha5Z/ha6Z).Similarly, the electronic correlation energy at the CBS limit ( E CBS c ) was calculated using an algebraic expression 113 for the two-parameter inverse cubic function described by Helgaker and co-workers 115 with two consecutive basis sets from either the a X Z or ha X Z series (denoted here as s Z and l Z for the smaller and larger basis sets, respectively).Independent estimates of electronic energies for the CCSD(T)/aQZ optimized structures near the CBS limit were also obtained from explicitly correlated CCSD and CCSD(T) computations 116–119 carried out with the corresponding a X Z-F12 and ha X Z-F12 families of basis sets ( X = D, T, Q, 5). 120,121 The results reported here were obtained with ansatz F12b and default auxiliary basis sets in the Molpro 2022 quantum chemistry program, 122–124 and the triples contributions were not scaled.…”

Conformational comparison of urea and thiourea near the CCSD(T) complete basis set limit

“…Canonical CCSD(T) relative electronic energies of the Y C(NH 2 ) 2 conformations were estimated at the complete basis set (CBS) limit using the XZ and aXZ basis set series following the procedure outlined elsewhere [86][87][88]. The three largest basis sets in each family (X = Q, 5, 6) were used to obtain the Hartree-Fock energy at the CBS limit using an algebraic form of the three-parameter exponential function proposed by Feller [89].…”

Does DFT work for H­­2O and H2S dimers?

“…To investigate the applicability of DFT in the eld of chemical physics, we have performed a systematic DFT study of water and hydrogen sul de dimers. There have been some studies that compare water and hydrogen sul de dimers [45][46][47]. However, to the best of our knowledge, for newly developed functionals, there have not been any studies addressing the following questions.…”