介绍
a post-processing code can calculate normalized trace of interatomic force constant tensors versus atomic distances from force_constants produced by phonopy. refer: nat. commun., 2014, 5, 3525.


具体公式
the interatomic force constant (ifc) tensor from first-principles calculation is

where e and rα represent energy and atomic position along α direction, respectively. by taking
trace of ifc tensors, we can assess bonding stiffness regardless of crystal structure or coordinate
system.

finally, we need to normalize the trace values of many materials to compare their interaction
ranges as in fig. 3, since different materials have slightly different bonding stiffness. the
normalization is done by the trace value of self-interaction force_constants.


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useage:
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1. chmod +x trace_ifc.x
2. phonon calculations with phonopy.
3. ./trace_ifc.x (it reads force_constants and sposcar produced by phonopy)
4. plot trace_ifc.dat with gunplot, python, or freemat and so on.
5. trace_ifc.dat 格式说明



[ Last edited by 漫天飘雪 on 2020-9-5 at 10:39 ]

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