[Pw_forum] About the method to obtain the common tangent for determing the phase transition pressure.

[红生 赵]

Dear all,

For the first-order phase transitions, the following criteria should be met: 
Pressures of the two phases are equal, i.e., 

P_{eq} = - \frac{{d{E_1}}}{{d{V_1}}} = - \frac{{d{E_2}}}{{d{V_2}}}

In other words, the P_{eq} is gradient of common tangent of the two phases E-V 
curves obtained from EOS fitting. 

This is a mathematical problem, but for the plot of this common tangent, can 
someone please give me some hints? What tools/softwares should I use for this 
purpose? Thanks in advance.

Best regards.
Hongsheng Zhao


      
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20101220/5c6aa29a/attachment.html>