View source for Solution LAB1 diamond bulk modulus


* Back to the previous page: [[Structural and electronic properties of semiconductors and metals #Convergences]]

===Bulk modulus of diamond===

Using the data produced in the previous exercise (total energy as a function of the lattice parameter for a range of ecutwfc values), one can do the following:
* extract etot vs volume for each wfcutfc value into different files;
* fit the data and extract the second derivative in the minimum;
* this can be done using a second (or better higher) order polynomial or other fitting functions (cubic splines, [https://en.wikipedia.org/wiki/Birch–Murnaghan_equation_of_state Murnaghan equation of state], ...)
* Evaluate the bulk modulus taking care of unit conversion to international system (B modulus is given in GPa)
* The above steps are coded in the script <code>./LabQSM/tools/compute_B_modulus.py</code> for convenience

Results as a function of the kinetic energy cutoff follow.