4.2 Coordinates and structure

The thermo_pw code requires the Bravais lattice of the solid. Moreover for computing some quantities it assumes that the direct lattice vectors are those provided by the routine latgen.f90 of the QUANTUM ESPRESSO distribution. For this reason it is not recommended to use ibrav=0 in the pw.x input. The preferred method is to give the value of ibrav and use the primitive vectors provided by QUANTUM ESPRESSO. It is also possible to specify the space_group number and the coordinates of the nonequivalent atoms. When the pw.x input contains the ibrav=0 option, thermo_pw writes on output the values of ibrav, celldm, and of the atomic coordinates that should be used in the input of pw.x to simulate the same solid and stops. There are however two input variables of thermo_pw that can modify this behavior:

continue_zero_ibrav : when ibrav=0 in the input of pw.x and 
             this variable is set to .TRUE. thermo_pw runs 
             with ibrav=0 (not recommended except when you 
             deal with a supercell). When this variable is 
             .FALSE. and ibrav=0 the behavior depends on 
             find_ibrav.
             Default : logical .FALSE.

find_ibrav : This variable is active only when continue_zero_
             ibrav=.FALSE.. When this variable is set to .TRUE. 
             and the input of pw.x has ibrav=0, thermo_pw finds 
             the values of ibrav, celldm, and of the atomic 
             positions that produce the same crystal and 
             continue the calculation. The geometry used by 
             thermo_pw might be rotated with respect to the 
             input and have different primitive vectors. When 
             this variable is .FALSE. the code stops after 
             writing in output ibrav, celldm, and the atomic 
             positions. These variables can be copied in the 
             pw.x input. Note that the automatic identification 
             of the lattice does not work for supercells.
             Default : logical .FALSE.