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<p class="MsoNormal"><span style="font-size:10.5pt;color:black;background:white">Dear QE-Environ users,</span><span style="font-size:10.5pt"><br>
<br>
<span style="color:black;background:white">I am trying to relax a Mg 2+ ions (solvated with 6 water molecules, as shown in the following figure) in the implicit water (using the SCCS model implemented in the Environ packages). The input file of the SCF calculation
is attached in the email and the SCCS model is listed as follows:</span><br>
<br>
<span style="color:black;background:white">&ENVIRON</span><br>
<span style="color:black;background:white"> !</span><br>
<span style="color:black;background:white"> verbose = 0</span><br>
<span style="color:black;background:white"> environ_thr = 5.d-4</span><br>
<span style="color:black;background:white"> environ_type = 'input'</span><br>
<span style="color:black;background:white"> env_static_permittivity = 80</span><br>
<span style="color:black;background:white"> env_electrostatic = .true.</span><br>
<span style="color:black;background:white"> env_surface_tension = 0.D0</span><br>
<span style="color:black;background:white"> env_pressure = 0.D0</span><br>
<span style="color:black;background:white"> !</span><br>
<span style="color:black;background:white">/</span><br>
<span style="color:black;background:white">&BOUNDARY</span><br>
<span style="color:black;background:white">/</span><br>
<span style="color:black;background:white">&ELECTROSTATIC</span><br>
<span style="color:black;background:white"> !</span><br>
<span style="color:black;background:white"> pbc_correction = 'parabolic'</span><br>
<span style="color:black;background:white"> pbc_dim = 0</span><br>
<span style="color:black;background:white"> !</span><br>
<span style="color:black;background:white"> tol = 1.d-20</span><br>
<span style="color:black;background:white"> mix = 0.6</span><br>
<span style="color:black;background:white"> !</span><br>
<span style="color:black;background:white">/</span></span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Roboto"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.5pt;font-family:Roboto"><img width="480" height="482" style="width:5.0in;height:5.0208in" id="Picture_x0020_1" src="cid:image001.png@01D7140F.617C73D0"><br>
<br>
</span><span style="font-size:10.5pt">However, I found the SCF is hard to get converged. Although I have tried using smaller tolerance in the polarisation calculations (tol = 1.d-20) and also smaller value of the mixing beta (0.05) in the outer SCF and even
starting the SCCS calculation when the outer SCF has converge into a quite small threshold (5.d -4), the SCF still cannot can converged. It seems that the SCF is failed at certain step, with the total energy changed tenuously (see the output file). <o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> iteration # 16 ecut= 70.00 Ry beta= 0.05<o:p></o:p></p>
<p class="MsoNormal"> CG style diagonalization<o:p></o:p></p>
<p class="MsoNormal"> ethr = 4.12E-06, avg # of iterations = 3.8<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> negative rho (up, down): 9.571E-03 0.000E+00<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> add environment contribution to local potential<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> total cpu time spent up to now is 3170.9 secs<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> total energy = -238.62974894 Ry<o:p></o:p></p>
<p class="MsoNormal"> Harris-Foulkes estimate = -238.63007614 Ry<o:p></o:p></p>
<p class="MsoNormal"> estimated scf accuracy < 0.00019209 Ry<o:p></o:p></p>
<p class="MsoNormal"> electrostatic embedding = 0.00036370 Ry<o:p></o:p></p>
<p class="MsoNormal"> correction to one-el term = 0.00000000 Ry<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> iteration # 17 ecut= 70.00 Ry beta= 0.05<o:p></o:p></p>
<p class="MsoNormal"> CG style diagonalization<o:p></o:p></p>
<p class="MsoNormal"> c_bands: 5 eigenvalues not converged<o:p></o:p></p>
<p class="MsoNormal"> ethr = 4.00E-07, avg # of iterations = 12.1<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> negative rho (up, down): 9.171E-03 0.000E+00<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> total cpu time spent up to now is 3573.5 secs<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> total energy = -369.87859582 Ry<o:p></o:p></p>
<p class="MsoNormal"> Harris-Foulkes estimate = -347.04441288 Ry<o:p></o:p></p>
<p class="MsoNormal"> estimated scf accuracy < 53.24399064 Ry<o:p></o:p></p>
<p class="MsoNormal"> electrostatic embedding = -0.57585314 Ry<o:p></o:p></p>
<p class="MsoNormal"> correction to one-el term = -22.25879718 Ry<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.5pt"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.5pt">Could you please give me any suggestions about this calculation and help me get over this convergence problem?<br>
<br>
I am looking forward to your reply.<br>
<br>
<br>
Best Regards,<br>
Bingxin Li</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
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