Local energy decomposition analysis and molecular properties of encapsulated methane in fullerene (CH₄@C₆₀)

Abstract

Methane has been successfully encapsulated within cages of C60 fullerene, and it is an appropriate model system to study confinement effects. Its chemistry and physics is also relevant for theoretical...

Improved Estimates of Host‐Guest Interaction Energies for Endohedral Fullerenes Containing Rare Gas Atoms, Small Molecules, and Cations

“…The interaction energy values for He@C 60 , Ne@C 60 , Ar@C 60 and Kr@C 60 obtained using the DLPNO‐CCSD(T)/def2‐TZVP methodology were found to be −1.4, −3.1 and −12.2, and −13.6 kcal/mol, respectively. Interestingly, our interaction energies for He@C 60 and Ne@C 60 are in good agreement with the ones reported by Hesselmann and Korona [59] using the DFT‐SAPT method, while the interaction energies for Ar@C 60 and Kr@C 60 are in excellent agreement with the ones reported by Jaworski and Hedin (DLPNO‐CCSD(T)) [45] . The difference between the two sets of results (ours and Jaworski et al.)…”

“…The difference between the two sets of results (ours and Jaworski et al.) presumably arises from the fact that Jaworski and Hedin [45] carried out PBE ‘‘revPBE’’ exchange‐correlation calculations in conjunction with an atom‐pairwise dispersion correction (D4) for geometry optimization, while we have used the DFT(MN15)/cc‐pVTZ method. Also, different basis sets were used in single‐point energy calculations.…”

“…Following the procedure adopted by Jaworski and Hedin, [45] the interaction energy was decomposed using the LED [57–58] protocol as implemented in ORCA, which allows for a physically meaningful decomposition, within the DLPNO‐CCSD(T) framework as follows: $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr \Delta E=\Delta {E}^{HF}+\Delta {E}^{C}\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr =\Delta {E}^{HF}+\Delta {E}^{C-CCSD}+\Delta {E}^{C-\left(T\right)}\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr =\Delta {E}^{HF}+\Delta {E}_{disp}^{C}+\Delta {E}_{non-disp}^{C}+\Delta {E}^{C-\left(T\right)}\hfill\cr}}$$$ $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr =\Delta {E}_{el-prep}^{HF}+{E}_{elstat}+{E}_{exch}\hfill\cr +\Delta {E}_{disp}^{C}+\Delta {E}_{non-disp}^{C}+\Delta {E}^{C-\left(T\right)}\hfill\cr}}$$$ …”

“…examined noble gas endohedral fullerenes and found that the Grimme functional B97 coupled with D2/D3 dispersion produced reliable interaction energies [44] . Recently, Jaworski and Hedin pointed out the importance of dispersion interaction in stabilizing the CH 4 @C 60 complex and the stabilization energy was found to be −13.5 kcal/mole at the domain‐based local pair natural orbital coupled‐cluster singles, doubles, and perturbative triples (DLPNO‐CCSD(T)) level of theory [45] . They have also studied the interaction energies for Rg @C 60 complexes and mentioned that He 2 @C 60 was thermodynamically stable.…”

Electron correlation and vibrational effects in predictions of paramagnetic NMR shifts

“…[90][91][92][93] Quantitative insights into challenging noncovalent interactions in endohedral fullerene complexes have for example been achieved with the DLPNO-CCSD(T) scheme in recent years. 94 A complementary formulation for high-spin open-shell systems has also been developed. 95,96 Moreover, within the DLPNO-CCSD scheme the use of L-equations for unrelaxed coupled cluster density provides spin densities and first-order properties.…”