[DFTB-Plus-User] How should I output GRADIENT, DIPOLE and so on...?

Ben Hourahine benjamin.hourahine at strath.ac.uk
Fri Apr 2 12:40:27 CEST 2010


Hello again,

> Hello Dr. B. Hourahine,
>
> Thank you for some answer.
> (1)Dipole moment  -> I'll be able to use DFTB+(1.1) (NOT Periodic
> neutral systems).
>    Can I print out Dipole moment of Periodic neutral systems with DFTB+(
> Version above 1.1) in the future?
>   
For periodic systems this requires the modern theory of polarization,
so it not currently implemented, but is on the development plan. For
a periodic system of finite molecules the Mulliken charges give a reasonable
approximation of the local molecular dipoles, so you could try 
evaluating them
from this information (look in detailed.out for the net atomic charges).

> (2)GRADIENT  ->  Cartesian Gradient
>    I mean the former (the energy derivative with position).
>   

The forces are the negative of this value, if you set

Driver = {}

Options = {
  CalculateForces = Yes
}

they are printed in detailed.out but other types of driver automatically
print them into that file as well.
> (3)Hessian  (Additional question)
>    How should I use Command of DFTB+ to print out Hessian, please?
>
>   

dftb+1.1 will have a driver to calculate the Hessian numerically.

Regards

Ben

>
>   
>> You can obtain part of the information you need with DFTB+.
>> The next release of DFTB+ (1.1) will print out the dipole
>> moment for non-periodic neutral systems.
>>
>> Generally in DFT the wavefunction is not an eigenstate of S**2,
>> except for the special case of closed shell systems. DFTB also has this
>> problem.
>>
>> Could you explain what the keyword 'GRADIENT' calculates? Does this
>> print the energy derivative with position, or is it the nuclear
>>     
> electric
>   
>> field gradient, or some other property?
>>
>> Regards
>>
>> Ben
>>
>> s043035 at center.wakayama-u.ac.jp wrote:
>>     
>>> Dear all,
>>>
>>>
>>>  I'm usually using both DFTB+ and Gaussian03.
>>>  I need and want to output GRADIENT and DIPOLE and S**2 in DFTB+.
>>>  GRADIENT and DIPOLE and S**2 is usually output in Gaussian03
>>>       
> outputfile
>   
>>> (*.log) or checkpoint file(*.chk).
>>>  How should I output those, please? (How shoul I use Command of DFTB+
>>>       
> ?)
>   
>>>  Thank you.
>>>
>>> -----------------------
>>>  Tokoyama
>>>       
>
>
>
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>   


-- 
     Dr. B. Hourahine, SUPA, Department of Physics,
   University of Strathclyde, John Anderson Building,
          107 Rottenrow, Glasgow G4 0NG, UK.
    +44 141 548 2325, benjamin.hourahine at strath.ac.uk
   The University of Strathclyde is a charitable body,
registered in Scotland, with registration number SC015263



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