Infrared spectroscopy and anharmonic theory of H3+Ar2,3 complexes: The role of symmetry in solvation

Abstract

The vibrational spectra of H3+Ar2,3 and D3+Ar2,3 are investigated in the 2000 cm−1 to 4500 cm−1 region through a combination of mass-selected infrared laser photodissociation spectroscopy and computational work including the effects of anharmonicity. In the reduced symmetry of the di-argon complex, vibrational activity is detected in the regions of both the symmetric and antisymmetric hydrogen stretching modes of H3+. The tri-argon complex restores the D3h symmetry of the H3+ ion, with a concomitant reduction in the vibrational activity that is limited to the region of the antisymmetric stretch. Throughout these spectra, additional bands are detected beyond those predicted with harmonic vibrational theory. Anharmonic theory is able to reproduce some of the additional bands, with varying degrees of success.

Performance of EOM-CCSD(T)(a)*-Based Quartic Force Fields in Computing Fundamental, Anharmonic Vibrational Frequencies of Molecular Electronically Excited States with Application to the Ã1A″ State of :CCH2 (Vinylidene)

“…Composite methods have exhibited such instability before, 44 but QFFs expanded with the exact same level of theory as the optimized geometry have been shown to perform much better. 102 Hence, the pure QZ QFF describes ν 3 better than CcCR. Since the quadratic terms are the dominant contributor to the QFF expansion, starting from the more descriptive CcCR harmonics and then conjoining these with more stable QZ cubic and quartic terms in the hybrid CcCR + QZ QFF produces the most accurate results in Table 4.…”

Trihydrogen Cation Helium Clusters: A New Potential Energy Surface

“…The vertex‐coordination of $${{H}_{3}^{+}-Ar}$$ is also supported by rotational/tunneling microwave spectroscopy [32–35] . Both ab‐initio Coupled Cluster formalism with single, double and (perturbative) triple excitations (CCSD(T)) and DFT (B3LYP, PW91 and BH&HLYP) [24–28,36–38] indicate that, when going to larger $${{H}_{3}^{+}{\left(Rg\right)}_{N}}$$ ( N ≥2), the liberated energy of the clustering reaction $${{H}_{3}^{+}{\left(Rg\right)}_{N}\to {H}_{3}^{+}({Rg)}_{N-1}+Rg}$$ tends to decrease by increasing N . Remarkable variations have been predicted between N =1 and N =2, and between N =3 and N =4.…”

“…In the case of H þ 3 Ar ð Þ N this result has been corroborated by Hartree-Fock Möller-Plesset (HF-MP2) calculations by Kaczorowska et al [31] The vertex-coordination of H þ 3 À Ar is also supported by rotational/tunneling microwave spectroscopy. [32][33][34][35] Both ab-initio Coupled Cluster formalism with single, double and (perturbative) triple excitations (CCSD-(T)) and DFT (B3LYP, PW91 and BH&HLYP) [24][25][26][27][28][36][37][38] indicate that, when going to larger…”

“…, the vibrational IR spectrum has been measured in the region of IR inactive symmetric stretching # 1 and IR active bending # 2 of the isolated H þ 3 . [38] The experimental spectrum of…”

“…In the case of $${{H}_{3}^{+}{\left(Ar\right)}_{N}}$$ , N =2, 3, the vibrational IR spectrum has been measured in the region of IR inactive symmetric stretching $${{\vartheta }_{1}}$$ and IR active bending $${{\vartheta }_{2}}$$ of the isolated $${{H}_{3}^{+}}$$ [38] . The experimental spectrum of $${{H}_{3}^{+}{\left(Ar\right)}_{2}}$$ is interpreted as a perturbed $${{H}_{3}^{+}}$$ with reduced symmetry $${\left({C}_{2v}\right)}$$ .…”