<div dir="ltr"><div>Hi Lucas,</div><div><br></div><div>Yeah, I tried to build a minimal example and I realized that this system doesn't convey what I really wanted to ask, that's why I deleted the question after I posted it. I apologize for the inconvenience, thank you though for taking time to look into it.</div><div><br></div><div>I wanted to look at the c-direction electron transfer in spin bi-layer bulk Hematite. I could always generate one state where Fe(III) has all five d-electrons spin down and the excess electron pairs up with one d-electron making it Fe(II). Let's say this is my initial state. And all the Fe(III) in one layer above or below this layer in c-dir have 5 d-electrons spin-up. When I try to localize an excess electron on one of these iron atoms in the second layer to generate a final state for electron transfer pathway I always end up with the electron going to the other spin-layer. I tried to relax multiplicity and started with a good initial guess using broken symmetry section. But, I see that more MO_beta orbitals are not accepted in cp2k by design, and it seems to be the case in all chemistry codes I came across. And also I can't specify the multiplicity to be zero considering I have an excess beta electron [2*(-0.5)+1 = 0], zero is the default value and multiplicity is evaluated to 2 with an excess electron, again placing it in alpha channel. It seems I am missing something basic here since negative spin multiplicities are not accepted. As you explained I think both states give the same energy and there is no need to place the excess charge in beta channel. There might be some other way to do these calculations if one wants to study anisotropy in c-dir of Hematite.<br></div><div><br></div><div>Thanks again.</div><div><br></div><div>Best regards,</div><div>Pavan.<br></div><br>On Friday, April 17, 2020 at 9:23:27 PM UTC-4, Lucas Lodeiro wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;"><div dir="ltr"><div>Hi Pavan, <br></div><div><br></div><div>I am not an expert on CP2K code, but in a theoretical point of view what you want to calculate is the same state, just in a different micro-state. <br></div><div>The case you show, or what ever case of duplet spin multiplicity has two micro-states (in the spin freedom degree), and both have the same energy (degenerated) and are described by the same spectroscopic term, but with different z spin projection. In both cases the quantum state for all properties is the same (except for Ŝ_z), then most of program, for simplicity, uses the alpha channel to project the spin.</div><div>For higher spin multiplicities, you have more micro-states for the same spectroscopic term, but is complex in some cases. The triplet example, you have 3 micro-states, S_z=+1,0,-1. The former and the latter are a single determinant and the only difference is the channels of the unpaired electrons (two), is a simple case as duplet multiplicity, but, the S_z=0 case is complex, due to this state is a linear combination of two determinants, and needs multi reference description. Then the full spin projection is a simpler case.</div><div><br></div><div>Only if you use a magnetic field, the degeneration is broken, and both cases you mention are differents.</div><div><br></div><div>Regards - Lucas Lodeiro<br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr">El jue., 16 abr. 2020 a las 17:38, pavan kumar behara (<<a href="javascript:" target="_blank" gdf-obfuscated-mailto="VE6jaZ6jAAAJ" rel="nofollow" onmousedown="this.href='javascript:';return true;" onclick="this.href='javascript:';return true;">pa...@gmail.com</a>>) escribió:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><span style="font-family:verdana,sans-serif">Hello CP2K developers,</span></div><div><span style="font-family:verdana,sans-serif"><br></span></div><div><span style="font-family:verdana,sans-serif">I notice that excess electrons are always assigned to alpha channel, is it possible to generate a configuration where I can have more beta electrons?</span><span style="font-family:verdana,sans-serif"> Let's consider a minimal example of hydrogen molecule with excess charge, H-H(-), making it a 3-electron system. I can always calculate [2 spin-up, 1 spin-down] configuration<br></span><div style="font-size:small;color:rgb(0,0,0)">
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<p class="MsoNormal" style="margin:0in 0in 0.0001pt;text-align:center;line-height:normal;font-size:11pt" align="center"><span style="font-family:verdana,sans-serif"><span style="color:red">↑</span><span style="color:red"><span></span></span></span></p>
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<td style="width:30.75pt;border-color:windowtext windowtext windowtext currentcolor;border-style:solid solid solid none;border-width:1pt 1pt 1pt medium;padding:0in 5.4pt;height:14.6pt" width="41" valign="top">
<p class="MsoNormal" style="margin:0in 0in 0.0001pt;text-align:center;line-height:normal;font-size:11pt" align="center"><span style="font-family:verdana,sans-serif"><span style="color:red">↑</span><b><span style="color:rgb(0,112,192)">↓</span></b><span style="color:red"><span></span></span></span></p>
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</div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif">but never [1 spin-up, 2 spin-down]<br></span></div><div style="font-size:small;color:rgb(0,0,0)">
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<p class="MsoNormal" style="margin:0in 0in 0.0001pt;text-align:center;line-height:normal;font-size:11pt" align="center"><span style="font-family:verdana,sans-serif"><span style="color:rgb(0,112,192)">↓</span><span style="color:rgb(0,112,192)"><span></span></span></span></p>
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<td style="width:30.75pt;border-color:windowtext windowtext windowtext currentcolor;border-style:solid solid solid none;border-width:1pt 1pt 1pt medium;padding:0in 5.4pt;height:14.6pt" width="41" valign="top">
<p class="MsoNormal" style="margin:0in 0in 0.0001pt;text-align:center;line-height:normal;font-size:11pt" align="center"><span style="font-family:verdana,sans-serif"><span style="color:rgb(0,112,192)">↓</span><b><span style="color:red">↑</span></b><span style="color:rgb(0,112,192)"><span></span></span></span></p>
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</div><div><span style="font-family:verdana,sans-serif"><br></span></div><div><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif">I
started with a spin-down hydrogen as initial atomic guess but the
density matrix is re-scaled before starting the SCF iterations making it
2 alpha and 1 beta. <br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif">Is there a way to get the second configuration or there is a reason not to do so? I attached the inputs and output for your reference.</span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif">Any help is appreciated, thank you very much for your time.</span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif">Best regards,</span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif">Pavan.<br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><br></span></div><div style="font-size:small;color:rgb(0,0,0)"><span style="font-family:verdana,sans-serif"><img alt=""><img alt=""><img alt=""><img alt=""></span></div></div></div>
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