Hi,

I am trying to calculate the pressure on a particular group of atoms using

the stress tensor example in the documentation. However when I try to get

the difference in pressure between the start of the run and the current

step, it gives the following error message:

p0_18942: p4_error: interrupt SIGSEGV: 11

Here is a code snippet, where it fails on the last line:

compute s all stress/atom

compute p all reduce sum c_s[1] c_s[2] c_s[3]

variable pressure equal -(c_p[1]+c_p[2]+c_p[3])/(3*vol)

variable diffPressure equal v_pressure-${pressure}

Using the global thermo pressure compute value works fine, but I want to be

able to calculate the pressure for a subgroup of atoms.

I am using version 21 May 2008. Is there something obvious that I'm missing?

Thanks in advance for your help.

Regards,

Anna.