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<br>
Hello,<br>
<br>
I try to do calculations for noncentrosymmetric superconductor
CaIrSi3 ( tetragonal BaNiSn3-type crystal<br>
structure, with space group I4mm (no. 107)) using QE 6.3: <br>
<br>
************************************************************************<br>
&SYSTEM<br>
ibrav = 0<br>
celldm(1)=7.90529<br>
nat=5<br>
ntyp=3<br>
<br>
/<br>
<br>
<br>
<br>
CELL_PARAMETERS alat<br>
1.000000000000000 0.000000000000000 0.000000000000000<br>
0.000000000000000 1.000000000000000 0.000000000000000<br>
0.500000000000000 0.500000000000000 1.180025338847321<br>
<br>
<br>
<br>
<br>
ATOMIC_POSITIONS (crystal)<br>
Ir 0.763090000000000 0.763090000000000 0.473820000000000<br>
Ca 0.409750000000000 0.409750000000000 0.180500000000000<br>
Si 0.650890000000000 0.150890000000000 0.698220000000000<br>
Si 0.150890000000000 0.650890000000000 0.698220000000000<br>
Si 0.000000000000000 0.000000000000000 0.000000000000000<br>
<br>
******************************************************************************<br>
<br>
scf goes fine and I get at the beginning of the output:<br>
<br>
bravais-lattice index = 0<br>
lattice parameter (alat) = 7.9053 a.u.<br>
unit-cell volume = 582.9680 (a.u.)^3<br>
number of atoms/cell = 5<br>
number of atomic types = 3<br>
<br>
<br>
celldm(1)= 7.905290 celldm(2)= 0.000000 celldm(3)=
0.000000<br>
celldm(4)= 0.000000 celldm(5)= 0.000000 celldm(6)=
0.000000<br>
<br>
crystal axes: (cart. coord. in units of alat)<br>
a(1) = ( 1.000000 0.000000 0.000000 )<br>
a(2) = ( 0.000000 1.000000 0.000000 )<br>
a(3) = ( 0.500000 0.500000 1.180025 )<br>
<br>
reciprocal axes: (cart. coord. in units 2 pi/alat)<br>
b(1) = ( 1.000000 0.000000 -0.423720 )<br>
b(2) = ( 0.000000 1.000000 -0.423720 )<br>
b(3) = ( 0.000000 0.000000 0.847439 )<br>
<br>
<br>
<br>
But when I start ph.x calculation (in the same folder using
exactly the same values) I get:<br>
<br>
<br>
bravais-lattice index = 0<br>
lattice parameter (alat) = 7.9053 a.u.<br>
unit-cell volume = 582.9680 (a.u.)^3<br>
number of atoms/cell = 5<br>
number of atomic types = 3<br>
<br>
<br>
<br>
celldm(1)= 15.81058 celldm(2)= Infinity celldm(3)=
0.68783<br>
celldm(4)= 0.00000 celldm(5)= 0.36346 celldm(6)=
0.00000<br>
<br>
crystal axes: (cart. coord. in units of alat)<br>
a(1) = ( 1.0000 0.0000 0.0000 )<br>
a(2) = ( 0.0000 1.0000 0.0000 )<br>
a(3) = ( 0.5000 0.5000 1.1800 )<br>
<br>
reciprocal axes: (cart. coord. in units 2 pi/alat)<br>
b(1) = ( 1.0000 0.0000 -0.4237 )<br>
b(2) = ( 0.0000 1.0000 -0.4237 )<br>
b(3) = ( 0.0000 0.0000 0.8474 )<br>
<br>
<br>
Why there are such differences in celldm? <br>
<br>
-- <br>
with regards<br>
<br>
Arena Konta<br>
The Institute of Thermophysics in Novosibirsk Scientific Center<br>
<br>
<br>
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