[QE-users] Why do I get a warning when using PWTK with HSE?

[NAIMI SALMA]

Hello everyone,

As I couldn't get the optimized lattice parameter for my material by vc-relax calculation, I used pwtk to get the optimized lattice parameter of my material with HSE.

In the input I used the experimental lattice parameter. But for the last calculated 2 points I get a warning in the terminal that the used a0 is too small even though that I used the experimantal one. That's the message that I receive :

```
------------------------------------------------------------------------
WARNING: from get2pV0_: two-point Murnaghan estimation of lattice-parameter failed.
                  The initial a0 was too small.
------------------------------------------------------------------------

      poor-man estimate of unit-cell volume :  V0 =  3536.06 bohr^3
      poor-man estimate of lattice-parameter:  a0 =    15.23 bohr


      warning: minimum is not bracketed yet, calculating another
               estimator point.

      * calculating estimator point #.5 :  a =  15.997 bohr

      Executable: /home/salma/Desktop/qe-7.0/bin/pw.x
      Running: pw.x -in my_input.d/my_input.estimator-5.in > my_input.d/my_input.estimator-5.out


      * E(tot) = -566.98612068 ryd
      * P      = 7.34 kbar


      warning: minimum is not bracketed yet, calculating another
               estimator point.
ABORT: cannot guess correct a0 in 5 steps. Initial a0 must be too far off, retry with better a0 estimation.
ABORT statement executed in: run_auto_ my_input.d/my_input
```

How can I solve this problem, please?


PS: I didn't face the same issue when working with PWTK and GGA, I got a lattice parameter close to the experimental one in the output.










------------------------------------------------------------
Salma NAIMI
PhD student - Mohamed 5 University-Rabat








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