Journal Article conformational analysis 9NEZ333N27 DLPNO-CCSD(T1) Ligands Metals, Alkali Research Support, Non-U.S. Gov't Sodium Solvents ab initio alkali metal ion clusters argon nitride atomization energies basis sets cationic noncovalent interactions cluster-continuum theory computational chemistry method testing diffuse functions enthalpy of formation formation enthalpy harmonic oscillator low vibrational frequencies microsolvation organic carbonate clusters quantum chemistry semiempirical methods sodium cation clusters solvent effects thermodynamic corrections thermodynamic functions