Eur. Phys. J. D (2016) 70: 176
https://doi.org/10.1140/epjd/e2016-70155-0

Regular Article

Free energy barrier for dissociation of the guanosine monophosphate anion in water^*

Instituto de Física, Universidade de São Paulo, Rua do Matão, 1371, 05508-090, São Paulo, SP, Brazil

^a e-mail: mvarella@if.usp.br

Received: 1 March 2016
Received in final form: 10 May 2016
Published online: 1 September 2016

Abstract

We report free energy barriers for the ground-state dissociation of the guanosine nucleotide anion in solution, employing implicit and explicit solvation models. The latter was based on the Free Energy Perturbation technique and Monte Carlo simulations. For the lowest-energy structure, both solvation models indicate a solvent-induced transition from a dipole-bound state in the gas phase to a π^∗ valence state in solution. The free barrier estimates obtained from explicit and implicit solvation are in fair agreement with each other, although significantly overestimated in comparison to a previously reported explicit solvation model based on ab initio molecular dynamics simulations. Accounting for corrections related to the different DFT functionals used in the present and previous studies significantly improves the agreement.