how to solve optamization problem in vnl?

[puspa raj adhikari]

Dear Quantum-wise staffs,
 
                                       i'm trying to optimise TiC nanotube of (14,14) armchair structure but could not success  and shows the error as mentioned below  attached file. plz help me how to solve this problem to optimise it? what is problem in Vnl behind it?

[Daniele Stradi]

Where is the error? The max. force in your system is lower than the threshold. Same for the stress. Lower the threshold and you will see that the system will start to optimize its geometry.

[puspa raj adhikari]

sorry, i cant understand, can u plz elaborate..
you mean here in calculator? i set the linear threshold to '0' and in geometry optimisation
the value for the stress and force is leave defult.. how can i lower the threshold below 0??
thank you sir fore ur response and hope u will again..  

[Anders Blom]

1. There is no error in the calculation (log file), so what are you actually asking?
2. Linear threshold is an expert option that should not be touched
3. The stress and force tolerance are the relevant parameters

[Daniele Stradi]

In your python input the thresholds are set to:

max_forces=0.05*eV/Ang,
max_stress=0.05*eV/Ang**3,

The calculated forces and stresses in the log file are:

Max force = 0.0465979 eV/Ang
Max stress =  0.003555 eV/Ang**3

Both are lower than max_forces and max_stress. To start seeing some relaxation, you should set in your python script something like:

max_forces=0.025*eV/Ang,
max_stress=0.0025*eV/Ang**3,

[puspa raj adhikari]

thank you sir, i got it..
but in this type( below attached) of error, how can i proceed??

       THANK YOU IN ADVANCE...

[Daniele Stradi]

I think the most likely thing is that you ran out of memory, your system is quite big and you are using a very outdated version of ATK.

[puspa raj adhikari]

haha may be...
thank you Mr Daniele...
i have tried on new version 16 (trial) but same problem encountered.
this must be due to lack of memory so leaving such big structures...
thanks all of u experts for your suggestion and hlp...