Michal, In addition to ESM (which, by the way, you should set nosym = .TRUE. when you use this method), you should also take a look at the electrostatic PBC corrections introduced by the Environ module (http://www.quantum-environ.org). Documentation for the methods in this module can be found on that website.
Best, Steve -- Stephen Weitzner, PhD Postdoctoral Research Scientist Quantum Simulations Group Lawrence Livermore National Laboratory T : (925) 422-4449 E : [email protected] On 4/3/20, 7:00 AM, "users on behalf of Giuseppe Mattioli" <[email protected] on behalf of [email protected]> wrote: Dear Michal I'm a fan of esm. If you want to study the adsorption of molecules inducing a strong vertical dipole you are forced to decouple such dipole along the z direction of the cell, otherwise you experiment an horrible "capacitor effect" on the potential curve. To use esm='bc1' (a vacuum-slab-vacuum geometry) you need to confine the electronic density of your system (the density, not the atoms...) between -l/4 and l/4 (you can shift the 0 of the cell if you don't want to shift the atoms), where l is the z edge of your supercell. I don't know if you consider this as an "enormous vacuum padding"... Moreover, esm produces "for free" a very useful file (in the TMP_DIR), namely prefix.esm1, where at the end of each scf iteration useful quantities are plotted, such as the electrostatic potential and the charge density integrated on x,y planes. You may want to have a look to this recent paper (J. Phys. Chem. C 2020, 124, 3601) to see what you can do with such data (e.g., calculate changes in the surface workfunction upon the adsorption of polar molecules). Finally, during the first scf iteration you may experiment a bit of instability, but it is generally not a dramatic problem... HTH Giuseppe Quoting Michal Krompiec <[email protected]>: > Hello, > I was wondering which assume_isolated method is the preferred choice > for calculation of adsorption energies of small molecules on 2D slabs > of metals and oxides. > So far, I've been using assume_isolated='2d', but it requires an > enormous vacuum padding. Is esm less resource-hungry? Does anyone use > a less accurate scheme first (e.g. no "assume_isolated" and a small > vacuum padding) and moves later to the target large cell with > assume_isolated=2d? > I understand that it all depends on the system, and that a convergence > test has to be done anyway, but I would be grateful for any tips. > > Thanks, > Michal Krompiec > Merck KGaA > _______________________________________________ > Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) > users mailing list [email protected] > https://lists.quantum-espresso.org/mailman/listinfo/users GIUSEPPE MATTIOLI CNR - ISTITUTO DI STRUTTURA DELLA MATERIA Via Salaria Km 29,300 - C.P. 10 I-00015 - Monterotondo Scalo (RM) Mob (*preferred*) +39 373 7305625 Tel + 39 06 90672342 - Fax +39 06 90672316 E-mail: <[email protected]> _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users _______________________________________________ Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso) users mailing list [email protected] https://lists.quantum-espresso.org/mailman/listinfo/users
