Single- and double-layer coupling of Schrِdinger and Poisson-Boltzmann equations

We present a method for incorporating solvent effects, including ionic strength, into ab initio electronic structure determinations and apply the method to the calculation of the free energy of solvation of the carbonate ion, CO32−. The Greenʹs function-based method couples the Schrödinger and linearized Poisson-Boltzmann equations through both the single and double layer surface charge distributions induced at a molecular-solvent interface. Single and double layers of charge are obtained from solution of the Poisson-Boltzmann equation (and added iteratively to the Hamiltonian) using electronic structure results (MP2/6–31G∗∗) directly, eliminating the uncertainty in employing fractional charges.