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<DIV>Dear all,</DIV>
<DIV> </DIV>
<DIV>For the first-order phase transitions, the following criteria should be met: Pressures of the two phases are equal, i.e., </DIV>
<DIV>P_{eq} = - \frac{{d{E_1}}}{{d{V_1}}} = - \frac{{d{E_2}}}{{d{V_2}}}</DIV>
<DIV> </DIV>
<DIV>In other words, the P_{eq} is gradient of common tangent of the two phases E-V curves obtained from EOS fitting. </DIV>
<DIV>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.</DIV>
<DIV> </DIV>
<DIV>Best regards.</DIV>
<DIV>Hongsheng Zhao</DIV>
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