[Pw_forum] Question on stress in a system with constraints

[Konstantin Kudin]

 Hi there,

 I have a basic question on the stress tensor.

 Presumably, the stress tensor computed in the CP implies continuous
stretching of the underlying system. Is this correct? Is the derivative
with respect to % of stretch, or is it to extra length in Bohrs, for
example?
What are the units of the stress in CP ?

 If one projected out certain forces (for constrained coordinates),
then the stress needs to be corrected for the fact that certain forces
are no longer there. Basically, the original stress was computed as if
all the forces were present, now, however, some of them are missing.
This means that if the system were to be stretched, the constrained
coordinates would still be constrained.

 My question is how I can correct the stress in a system with
constraints if this needs to be done.

 Thanks!
 Kostya


		
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