Hi Abraham, follows the file .fdf to see if you can help me.
argon dimer calculations showed acceptable results with the vasp and g03 programs. thanks, Vitor. 2013/6/27 Abraham Hmiel <[email protected]> > Hello Vitor, > > GGA functionals typically do a poor job of capturing the physics of > systems with strong van der Waals character like the Ar dimer. Typically > LDA performs better than GGA because of fortunate cancellation of error, > but is still far from correct. > > Try installing a recent version of SIESTA's development trunk, available > from the website. You will be able to use the vdW-DF (DRSLL), vdW-DF2 > (LMKLL), and opt-b88 (KBM) functionals which may significantly improve your > Ar-Ar bond distance and binding energy at the expense of additional time > spent calculating the xc energy. There is a decent pool of computational > results in the literature to draw from here, as well. > > Furthermore, these self-consistent vdW functionals will give you the tools > to engineer a better optimized basis for Ar. Using an optimized basis > rather than the automatically-generated ones can be useful and it probably > couldn't hurt to add additional zetas, polarization orbitals and diffuse > orbitals to your basis. Without your .fdf file though, it's difficult to > give you a more exact perscription, but using some form of vdW-DF could be > a decent start, I feel. > > Best of luck, > > > On Thu, Jun 27, 2013 at 2:28 PM, Vitor Damiao <[email protected]>wrote: > >> Hi all, >> >> Have anybody calculated the argon dimer with SIESTA program? It appears >> that the binding energy (BE) is overestimated. Please, see a DFT-PBE >> calculation using a DZP basis set for Ar---Ar: >> BE (DFT) = 1.3 kcal/mol >> BE (DFT+D) = 2.4 kcal/mol >> BE (Expt.) = 0.28 kcal/mol >> >> I have tried using different pseudopotentials schemes, but the binding >> energies appears to be too high. I would be grateful if someone could >> explain me this trouble. >> >> Thanks in advance >> Vitor >> > > > > -- > *Abraham Hmiel* > Katherine Belz Groves Fellow in Nanoscience > Xue Group, College of Nanoscale Science and Engineering at SUNY Albany > http://abehmiel.net/about > >
ar2.fdf
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