I am looking for some guidance on using forcite module for mechanical property. I'm creating crystal and when trying to do geometry optimization, selecting Compass, while assigning manually, getting some error. Am I missing something. Can you suggest some example manual for forcite module? Thanks.
Error : The forcefield type calculation failed.
The last error reported was:
The typing engine has failed to calculate a forcefield type for 26 particles.
Try using a different forcefield or assign types manually (and remember to turn off the automatic calculation of forcefield types).
Press Yes to select atoms that have not been typed.
Press No to carry on
You can try to assign force field to specific particle. The tutorial "Coarse-grained molecular dynamics of a lipid bilayer" in the help file may be helpful for your case.
Hi Radha,
I have build my cell (Pure Ni) and then have build nano cluster with substitution of Ga. Then I am trying to do geometry optimization. Compass is not working. Unable to assign Ga. But using universal forcefield I am able to assign Ni and Ga and calculate. But I am not sure about how to choose algorithm. How do I know which algorithm will give best convergence? My next step is to run mechanical property. I want to get Elastic modulus.
Another issue is for clusters unable to run mechanical property , It is highlighted.
You need to confirm whether the nanocluster is in crystal form or enclosed in a unit cell. This is because MD simulation can only be conducted on crystal structures/models or structures/models enclosed in confined space (unit cell).
Try if you can make supercell with your specified composition. And compass forcefield works for most of the elements (i.e yields good convergence). Additionally, try using random velocities in place of current.
I'm confused that this problem still exists, when i change the forcefield type in any case . In addition, when i assign a special forcefield type to all type atoms, the error is "Not all particles belong to a charge group.", but i don't know how to dispose this problem. can everybody give me some useful advises?
p.s. my cell is TiAlC2
Dear Ms. Dutta;
Some many things can be ocurring on your set up/running calculation. Here are some possible issues:
1) System should be a periodic crystal, with no neighboor atoms overlapping. To check this, you need to select right-click on your model and then select the option of display style and on lattice increase to see if your periodic conditions are fine. If there is overlapping, then your calculation will always fail.
2) Once you check all the atoms are in right position, I recommend to do a Geometrical Optimization using CASTEP. And selecting all tabs as coarse on SFC, Cutoff and just for Gamma point. This will allow the system to relax and to have an optimized structure with minimal computation time.
3) Once you have the optimized structure, then you can start running your forcefield. Now the question is: What are the exact properties you are looking for in your system? Elastic constants, optimization of lattice parameters?
4) Lastly, even though when is said that MS can run on any PC with minimal RAM of 4GB. I found that this is not absolutely true. Because, the optimization of cell is done every 60sec thus the video card on your hardware also plays an important role. Make sure, you have the appropiate computational resources. And that your license is also complete, some academic licenses are not bought for full access, then this can cause some issues. I will recommend this good literature about setting up calculations:
https://arxiv.org/pdf/1212.2280.pdf
But, use search engine and look for Harold S. Park of Boston University, that professor does a lots of good mechanical properties calculations on some exotic/complicated systems.
Good luck and best for you...
Manuel
ps. Look at my profile and please if you consider my work important and useful please cite it.
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