Dear all, Recently I am using Environ + QE to calculate the work function of Mg(0001) surface in different environment (vacuum/implicit water). Firstly I was doing a geometry optimisation calculation of Mg(0001) slab without environment packages. In this case, the fermi energy of the slab is -0.2249 eV and the vacuum potential is around 3.4713 eV(obtained using the pp.x and avg.x). Therefore, the work function can be simply calculated using 3.4713 – (-0.2249) = 3.6962 eV (which is close to the reference value: 3.62 eV).
Then I use the environment packages and turn on the implicit model, the input file for the environment part is as follows: &ENVIRON ! verbose = 0 environ_thr = 1.D0 environ_type = 'input' env_static_permittivity = 78.3(water)/1(vacuum) env_surface_tension = 0.D0 env_pressure = 0.D0 env_electrostatic = .true. ! / &BOUNDARY ! solvent_mode = 'full' ! / &ELECTROSTATIC ! pbc_correction = 'parabolic' pbc_dim = 2 pbc_axis = 3 tol = 5.D-13 ! / The calculations for the slab in vacuum/water were done without any errors. However, in the vacuum case, the fermi energy (considering the parabolic correction) of the slab is -3.2031 + 0.4671 = -2.736 eV. The vacuum (enviroment) potential is 3.105 eV (using pp.x and avg.x). The work function is vacuum with the environment package is 3.105 - (-2.736) = 5.841 eV, which is not correct. I guess this error answer is due to the wrong vacuum potential. That is to say, the environment potential in this case should not calculate in the normal way (pp.x + avg.x) or the environment potential should be corrected in some way. However, I have no idea about how to obtain the correct environment(vacuum/water) potential when the environment packages are used. I was wondering that could anyone who knows how to calculate the work function of the metal slab in the implicit environment correctly please help me on this issue? I am looking forward to your reply. Best Regards, Bingxin
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