Efficient multidimensional free energy calculations for ab initio molecular dynamics using classical bias potentials

We present a method for calcg. multidimensional free energy surfaces within the limited time scale of a first-principles mol. dynamics scheme. The sampling efficiency is enhanced using selected terms of a classical force field as a bias potential. This simple procedure yields a very substantial increase in sampling accuracy while retaining the high quality of the underlying ab initio potential surface and can thus be used for a parameter free calcn. of free energy surfaces. The success of the method is demonstrated by the applications to two gas phase mols., ethane and peroxynitrous acid, as test case systems. A statistical anal. of the results shows that the entire free energy landscape is well converged within a 40 ps simulation at 500 K, even for a system with barriers as high as 15 kcal/mol. [on SciFinder (R)]


Published in:
Journal of Chemical Physics, 113, 12, 4863-4868
Year:
2000
Laboratories:




 Record created 2006-02-27, last modified 2018-03-17


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