[QE-users] Scaling factor for

[Siebe Vanlommel]

Hi all,

I am trying to figure out whether there is a way to scale all three unit cell vectors at once in QE using pw.x. In my input file, I am using the CELL_PARAMETERS card (in units of Angstrom) to specify a unit cell. This (https://www.mail-archive.com/users@lists.quantum-espresso.org/msg19387.html) old post seems to suggest that the 'A' parameter in the &SYSTEM section acts as a scaling parameter if 'ibrav==0' and the CELL_PARAMETERS card is used to specify the lattice. I take this to mean that each lattice vector is multiplied by *A, where A is a dimensionless number. However, QE complains that:
"Error in routine cell_base_init (2):
     lattice parameter specified twice"

I've tried specifying the atomic positions in 'crystal' (fractional) coordinates and in Angstroms but to no use. Input file is attached below. I'm using QE version 6.4.1.

Is the interpretation of A as a scaling parameter with these settings deprecated, or am I missing something?

Thanks in advance,
Siebe

input file:

 &CONTROL
                       title = 'cha' ,
                 calculation = 'scf' ,
                  wf_collect = .true. ,
               etot_conv_thr = 1.0D-6 ,
 /
 &SYSTEM
                       ibrav = 0,
                           A = 1.2,
                         nat = 108,
                        ntyp = 2,
                     ecutwfc = 100 ,
                       nosym = .true. ,
 /
 &ELECTRONS
           scf_must_converge = .true. ,
 /
CELL_PARAMETERS angstrom
    13.738516409   -0.000070574    0.000007978
    -6.869319180   11.897869408   -0.000009602
     0.000010055   -0.000007302   14.715552482
ATOMIC_SPECIES
    O   15.99940  O.pbe-rrkjus.UPF
   Si   28.08551  Si.pbe-rrkj.UPF
ATOMIC_POSITIONS crystal
O     0.901932010         0.098069851         0.126854702
O     0.098068745         0.901933544         0.873144107
O     0.901940529         0.803877937         0.126862649
O     0.098062465         0.196127742         0.873139246
(...)
K_POINTS gamma
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