Dear All, I am writing to get some suggestions on computing the value of Z2 of a 1D organic polymer. I am getting the value 0.0 running the program with Quantum Espresso (7.2) and Wannier90. The last two lines are as below:

----------------------------------------------- Z2 topological invariant at kx = 0: 0 Z2 topological invariant at kx = 0.5: 0 -------------------------------------------

I would like to give some information about the QE set up. for thecaluation I am using PBE with ultrasoft pseudopotential. The k point mesh is 12*1*1. The ibrave=0 and the cell_parameters are given in angstroms at the end. Please let me know if you want to know any additional details.

The problem is I was expecting the value of Z2=1.0 for this system which was reported earlier.

Therefore, my question is if there are any options to rerun the calculation with different parameters which can alter the Z2 value to 1.0 from 0.0.

Any suggestions would be highly appreciated.

thanks Rameswar