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QuantumATK => General Questions and Answers => Topic started by: Vishal Tiwari on July 4, 2016, 23:46

Title: Atomic positions of strained Si lattice by adding Ge
Post by: Vishal Tiwari on July 4, 2016, 23:46

Hi,

I am defining a bulk Si lattice and then I extract the atomic positions of Si lattice. After adding a fixed fraction of Ge into it, how can i get/extract new atomic positions of the strained lattice?

Title: Re: Atomic positions of strained Si lattice by adding Ge
Post by: Ulrik G. Vej-Hansen on July 5, 2016, 10:32

Would you like to calculate the new equilibrium lattice constant, or simply extract the coordinates? The latter is done in exactly the same way also after you substitute the Ge.

Title: Re: Atomic positions of strained Si lattice by adding Ge
Post by: Vishal Tiwari on July 5, 2016, 11:26

As i am replacing some Si atoms with Ge, this will introduce strain in the lattice and lead to atomic displacements of the original lattice positions. So, i need to extract the new atomic positions and the atomic displacements because of strain.

Title: Re: Atomic positions of strained Si lattice by adding Ge
Post by: Ulrik G. Vej-Hansen on July 5, 2016, 11:51

In that case, you need to do a GeometryOptimization with your chosen computational model, both before and after inserting the Ge. This procedure is described in the beginning of this tutorial: http://docs.quantumwise.com/tutorials/formation_energies.html

You can then get the coordinates directly from the output of the calculations or extract them from the BulkConfiguration afterwards.