Dear all,

I am simulating CNTs and trying to calculate stress along radius. there is no output for stress vector (rr) as like (xx/yy/zz) directly, so I used the command **compute stress/atom** :

```
> compute atomS all stress/atom NULL
> variable atomR atom "sqrt(c_atomS[1]^2+c_atomS[2]^2)"
> ### stress(rr) =sqrt(stress(xx)^2+stress(yy)^2)
> compute PperS all reduce sum c_atomS[1] c_atomS[2] c_atomS[3] v_atomR
> variable Pcompt equal "-(c_PperS[1]+c_PperS[2]+c_PperS[3])/(3*vol)"
> variable Sxx equal "(c_PperS[1])/(vol)/10000"
> variable Syy equal "(c_PperS[2])/(vol)/10000"
> variable Szz equal "(c_PperS[3])/(vol)/10000"
> variable Srr equal "(c_PperS[4])/(vol)/10000"
```

Results agree with the manual : **Pcompt==Press; Sxx==Pxx(/10000)**; y; z, **BUT Srr is only half as expected.** Is the formula feasible to calculate **Srr**？

Any help will be greatly appreciated.

Best regards,

NingN