Dear Ian > I am thinking of examples where, for example, a vdW adlayer (e.g. benzene) > sits on a surface, and surface doesn't need vdW corrections.
In my opinion, your premise is false. molecule-surface interactions generally *do need* vdW corrections very badly! You may say that DFT-D2 (vdw_corr='grimme-d2') overestimates vdW forces between molecules and transition metal or metal-containing surfaces. DFT-D3 corrects such a behavior, but it is regretfully still not implemented in QE. However, I've obtained very good results by using one of the several ab initio vdw-df schemes, e.g. input_dft='vdw-df-c09'. If you want to stick to vdw_corr='grimme-d2', then you may follow Evren's suggestion and you can tune (not suppress) the surface C6 coefficients in order to avoid a too strong interaction between molecule and surface. HTH Giuseppe Quoting Ian Shuttleworth <[email protected]>: > Is it possible to apply vdW forces to only a part of system? > > I am thinking of examples where, for example, a vdW adlayer (e.g. benzene) > sits on a surface, and surface doesn't need vdW corrections. > > If I add the vdw_corr toggle (or if I set an appropriate value > to 'input_dft') I've understood that vdW are applied to the entire system - > if this is right, how could I make this option more selective? > > With thanks > > Ian -- ******************************************************** - Article premier - Les hommes naissent et demeurent libres et égaux en droits. Les distinctions sociales ne peuvent être fondées que sur l'utilité commune - Article 2 - Le but de toute association politique est la conservation des droits naturels et imprescriptibles de l'homme. Ces droits sont la liberté, la propriété, la sûreté et la résistance à l'oppression. ******************************************************** Giuseppe Mattioli CNR - ISTITUTO DI STRUTTURA DELLA MATERIA v. Salaria Km 29,300 - C.P. 10 I 00015 - Monterotondo Stazione (RM) Tel + 39 06 90672342 - Fax +39 06 90672316 E-mail: <[email protected]> http://www.ism.cnr.it/en/staff/giuseppe-mattioli/ ResearcherID: F-6308-2012 _______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
