How to fix O-H bond

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Junbo Lu

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Nov 27, 2021, 10:54:43 AM11/27/21
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Hello everyone,
  I need to fix the O-H bond for my system. I have searched the previous post. It seems that we just need to write such entry in MOTION section:
   &CONSTRAINT
    &HBONDS
    &END HBONDS
  &END CONSTRAINT
   Do we need to set other parameters? Could anyone give a help? I would be very appreciated!
   With my best regards,
  Junbo

Dawid das

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Nov 28, 2021, 1:19:33 PM11/28/21
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Hi,

This part of input will simply constrain all bond lengths at their initial value given the bond is between H and any other atom. I think that it is only important that atom name type starts with H. Otherwise it is not recognized as a hydrogen.

Junbo Lu

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Nov 28, 2021, 9:43:22 PM11/28/21
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Hi,
  Thank you very much! Do you have some detailed input? I have seen the manual about this section, but I am still confused with some keywords:
  (1) How do we set ATOM_TYPE? Do I need to set MOLNAME and MOLECULE? It seems that these two keywords are about QM/MM. My system contains a lot of H2O, OH- and Na+, and the coordination section is:
Na    9.215   6.592   1.668
Na   14.130  14.360   2.607
O     9.966  14.063  13.214
H     9.488  14.543  12.480
H    10.743  13.638  12.750
O    13.501   5.419  14.746
H    13.691   5.028  13.845
H    12.615   5.047  15.023
O     7.910   9.825   6.157
H     7.948   9.265   5.391
O     7.189   5.650   9.573
H     6.475   5.731   8.952
...
  (2)  In my system, the Na has no bonds with H. If I just use such simple input entry,  will the Na-H bond be fixed?
  With my best regards,
  Junbo

'Dawid das' via cp2k <cp...@googlegroups.com> 于2021年11月29日周一 上午2:19写道:
Hi,

This part of input will simply constrain all bond lengths at their initial value given the bond is between H and any other atom. I think that it is only important that atom name type starts with H. Otherwise it is not recognized as a hydrogen.

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