Id f f f f x ln ω rω rω rω r d d t k f b id ω r

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id F F F F x 0 0 ln Ω r, Ω r, Ω r, Ω r d d T k F B id Ω r, Ω r, Ω r ext ext V d d F 2 2 2 1 2 1 2 2 1 1 1 1 ) , , ( 2 1 Ω , r Ω Ω r r Ω r Ω , r Ω r c d d d d F exc V exc ( r 1 , 1 )
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Step 2: Minimization of the discretized functional Discretization of on a cubic grid for positions and Gauss-Legendre grid for orientations (typically 64 3 x 32) 2 , , Ω r Ω r Minimization in direct space by quasi-Newton (BFGS-L) (8x10 6 variables !!) • 2 x N = 64 FFTs per minimization step ~20 s per minimization step on a single processor
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MD DFT Solvent structure Na + Na Solvation in acetonitrile: Results MD DFT
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Solvation in acetonitrile: Results MD (~20 hours) DFT (10 mn)
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Solvation in acetonitrile: Results Halides solvation free energy Parameters for ion/TIP3P interactions
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Solvation in SPC/E water Solute-Oxygen radial distribution functions MD DFT Z X Y Three angles: , ,
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CH 3 C N Solvation in SPC/E water
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Cl -q Solvation in SPC/E water
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Solvation in SPC/E water Water in water HNC PL-HNC HNC+B g OO ( r )
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Conclusion DFT One can compute solvation free energies and microscopic solvation profiles using « classical » DFT Solute dynamics can be described using CPMD-like techniques For dipolar solvents, we presented a generic functional of or Direct correlation functions can be computed from MD simulations For general solvents, one can use angular grids instead of rotational invariants expansion r P BEYOND: -- Ionic solutions -- Solvent mixtures -- Biomolecule solvation r P r , n R. Ramirez et al, Phys. Rev E, 66 , 2002 J. Phys. Chem. B 114 , 2005 Chem. Phys. 2005 L. Gendre at al, Chem. Phys. Lett. S. Zhao et al, In prep.
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DCMD: « Soft pseudo-potentials » V(r) r V( r ) = ( r) -1 = 4 /( ( r )-1) V(r) r ) ( 1 1 1 1 r r H s i s =0
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Dielectric Continuum Molecular Dynamics Hexadecapeptide P2 La 3+ Ca 2+
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DCMD: Computation times Each time step correspond to a solvent free energy , thus an average over many solvent microscopic configurations linear in N !
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  • Fall '19
  • Computational chemistry, Molecular dynamics, Implicit solvation, Biomolecule solvation

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