[ase-users] C2 dimer convergence problem

[John Kitchin]

I have occasionally had problems with oxygen like this, and it sometimes
helps to change the mixing parameters and convergence criteria:

              convergence={'energy':1e-4,
                           'density':0.001},
              charge_mixing={'mixinghistory':5,
                             'mixingcoeff':0.05}


I am not sure what mixing will be helpful for you, but decreasing the mixing
will reduce the sloshing. the convergence criteria depends on your needs.
0.1 meV is good enough for energy calculations for me.

see

http://beowulf.cheme.cmu.edu/jacapo/1-molecules/1.4-spin-polarization/1.4.0-spin-polarization.html


John

-----------------------------------
John Kitchin
Assistant Professor
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
http://kitchingroup.cheme.cmu.edu




On Fri, Oct 15, 2010 at 9:00 PM, Huang Bing <hbdft2008 at gmail.com> wrote:

> I mean it fails to converge, resulting in an unusual oscillation of density
> and energy.
> I also noticed for transition metal dimer or atom, the convergence is
> worse. So, is
> there alternative i can choose except that mentioned in that link to
> improve convergence?
>
> 2010/10/16 John Kitchin <jkitchin at andrew.cmu.edu>
>
> Your interpretation is how I would interpret that. But since you don't say
>> what you mean by it not working, I don't know how to help you.
>> John
>>
>> -----------------------------------
>> John Kitchin
>> Assistant Professor
>> Doherty Hall A207F
>> Department of Chemical Engineering
>> Carnegie Mellon University
>> Pittsburgh, PA 15213
>> 412-268-7803
>> http://kitchingroup.cheme.cmu.edu
>>
>>
>>
>>
>>
>> On Fri, Oct 15, 2010 at 6:01 AM, Huang Bing <hbdft2008 at gmail.com> wrote:
>>
>>> Hi,
>>> I got stuck with the convergence problem of C2 dimer relaxation.
>>> I've tried everything except the last one suggested in the link:
>>> http://beowulf.cheme.cmu.edu/jacapo/troubleshooting.html<http://beowulf.cheme.cmu.edu/jacapo/troubleshooting.html#poor-convergence-of-atoms-molecules>
>>> #poor-convergence-of-atoms-molecules<http://beowulf.cheme.cmu.edu/jacapo/troubleshooting.html#poor-convergence-of-atoms-molecules>
>>>
>>> I interpret the lines
>>> """
>>> So start out with:
>>>
>>> ft = 0.2 (or 0.1, whatever works)
>>>
>>> iterate for a while and converge the density if possible, and then use:
>>>
>>> ft = 0.0001
>>> """
>>> as first we relax the C2 dimer with ft=0.2 and then we restart the
>>> relaxation based on the optimzed geometry and density with ft=0.001,
>>> I found it not working, is there anything wrong with my understanding?
>>>
>>>
>>>
>>
>
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