[CP2K-user] Spin contamination in condensed molecular liquid system
Tom H
tom.... at gmail.com
Mon May 31 12:06:16 UTC 2021
Hi all,
I am investigating a molecular liquid system, namely liquid-Se. It is
formed of short chains of Se (down to only 2 Se atoms), which may show
partially occupied electronic states, especially in the low pressure
regime, in which molecules are well separated. I am slightly confused about
how to model such a system using CP2K.
I have started running unrestricted Kohn-Sham MD calculations, starting
from an amorphous configuration of Se8 molecules in a chain configuration.
I do have an even number of electrons, but I am suspecting spin
polarization due to the reasons mentioned above. I've been checking for
spin contamination in the CP2K output, and obtained the following for the
first 100 steps of dynamics:
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
-0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000000
Ideal and single determinant S**2 : 0.000000
0.000002
Ideal and single determinant S**2 : 0.000000
0.000018
Ideal and single determinant S**2 : 0.000000
0.000152
Ideal and single determinant S**2 : 0.000000
0.001315
Ideal and single determinant S**2 : 0.000000
0.012071
Ideal and single determinant S**2 : 0.000000
0.108839
Ideal and single determinant S**2 : 0.000000
1.570334
Ideal and single determinant S**2 : 0.000000
8.075949
Ideal and single determinant S**2 : 0.000000
12.475536
Ideal and single determinant S**2 : 0.000000
14.594641
Ideal and single determinant S**2 : 0.000000
15.297790
Ideal and single determinant S**2 : 0.000000
16.214178
Ideal and single determinant S**2 : 0.000000
16.323013
Ideal and single determinant S**2 : 0.000000
16.129883
Ideal and single determinant S**2 : 0.000000
15.688840
Ideal and single determinant S**2 : 0.000000
15.961233
Ideal and single determinant S**2 : 0.000000
15.596193
Ideal and single determinant S**2 : 0.000000
15.578972
Ideal and single determinant S**2 : 0.000000
15.859515
Ideal and single determinant S**2 : 0.000000
15.810544
Ideal and single determinant S**2 : 0.000000
14.870891
Ideal and single determinant S**2 : 0.000000
14.549977
Ideal and single determinant S**2 : 0.000000
14.490598
Ideal and single determinant S**2 : 0.000000
14.477700
Ideal and single determinant S**2 : 0.000000
14.251470
Ideal and single determinant S**2 : 0.000000
14.256963
Ideal and single determinant S**2 : 0.000000
14.245575
Ideal and single determinant S**2 : 0.000000
14.657994
Ideal and single determinant S**2 : 0.000000
14.097974
Ideal and single determinant S**2 : 0.000000
14.181373
Ideal and single determinant S**2 : 0.000000
14.265038
Ideal and single determinant S**2 : 0.000000
14.134708
Ideal and single determinant S**2 : 0.000000
14.176089
Ideal and single determinant S**2 : 0.000000
14.011084
Ideal and single determinant S**2 : 0.000000
14.038357
Ideal and single determinant S**2 : 0.000000
14.313602
Ideal and single determinant S**2 : 0.000000
14.458239
Ideal and single determinant S**2 : 0.000000
14.474756
Ideal and single determinant S**2 : 0.000000
15.064850
Ideal and single determinant S**2 : 0.000000
15.349064
Ideal and single determinant S**2 : 0.000000
15.697990
Ideal and single determinant S**2 : 0.000000
15.740888
Ideal and single determinant S**2 : 0.000000
15.605483
Ideal and single determinant S**2 : 0.000000
15.619671
Ideal and single determinant S**2 : 0.000000
16.146289
Ideal and single determinant S**2 : 0.000000
16.571982
Ideal and single determinant S**2 : 0.000000
16.791026
Ideal and single determinant S**2 : 0.000000
16.182009
Ideal and single determinant S**2 : 0.000000
16.201162
Ideal and single determinant S**2 : 0.000000
16.799011
Ideal and single determinant S**2 : 0.000000
17.191503
Ideal and single determinant S**2 : 0.000000
16.657538
Ideal and single determinant S**2 : 0.000000
16.398196
Ideal and single determinant S**2 : 0.000000
16.685182
Ideal and single determinant S**2 : 0.000000
17.269278
Ideal and single determinant S**2 : 0.000000
17.420976
Ideal and single determinant S**2 : 0.000000
17.327620
Ideal and single determinant S**2 : 0.000000
17.123223
Ideal and single determinant S**2 : 0.000000
17.213689
Ideal and single determinant S**2 : 0.000000
17.264376
Ideal and single determinant S**2 : 0.000000
17.123970
Ideal and single determinant S**2 : 0.000000
16.758495
Ideal and single determinant S**2 : 0.000000
16.487501
Ideal and single determinant S**2 : 0.000000
16.738201
Ideal and single determinant S**2 : 0.000000
16.527679
Ideal and single determinant S**2 : 0.000000
16.042440
Ideal and single determinant S**2 : 0.000000
15.726199
Ideal and single determinant S**2 : 0.000000
15.538890
Ideal and single determinant S**2 : 0.000000
15.731163
Ideal and single determinant S**2 : 0.000000
15.596686
Ideal and single determinant S**2 : 0.000000
15.086832
Ideal and single determinant S**2 : 0.000000
15.170306
Ideal and single determinant S**2 : 0.000000
14.774768
Ideal and single determinant S**2 : 0.000000
14.358169
Ideal and single determinant S**2 : 0.000000
14.818519
Ideal and single determinant S**2 : 0.000000
15.032944
Ideal and single determinant S**2 : 0.000000
14.517417
Ideal and single determinant S**2 : 0.000000
14.088642
Should I be bothered? Over this short MD run, some Se8 chains already break
into smaller chunks - so I'm expecting more singly-occupied electronic
states than at the beginning. I'm having a hard time understanding the
connection between spin polarization in the "isolated, single molecule"
formalism of CP2K and spin polarization in condensed molecular systems.
One last question : any tips on accelerating SCF convergence of UKS related
to the OT method?
thank you,
Tom
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