Dear Alessandro,
thank you for this explanation!
Kind regards,
Georg

Dear Alessandro,
dear crystal-developers,

do I understand correctly that the QHA in crystal is based on gamma-point phonons only?

Thank you!
Kind regards,
Georg

Hi Alessandro,
thank you very much for these detailed explanations!
Crystal is an amazing program, and I am just starting to explore its powerful thermoelastic capabilities.
Kind regards,
Georg

Dear Alessandro,
thank you for your quick answer!
Can you give me a hint where to find the optimized cells from the EOS calculations?
I was irritated, because that in the log file only the EOS-volumes are indicated, but not the angles.
And in the QHA-output, naturally only the lattice constants a,b,c are reported, again not angles.

The EOS-output looks like this:
EOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOSEOS
VOLUME (A^3) ENERGY (a.u.) DIFFERENCE RELATIVE
TO CENTRAL
3.23014700E+02 -4.11365657E+03 2.41646382E-03
3.43259302E+02 -4.11365655E+03 2.43344879E-03
3.53634103E+02 -4.11364971E+03 9.27344625E-03
SORTING VOLUMES/ENERGIES
VOLUME (A^3) ENERGY (a.u.)
323.014700 -4.113656565586E+03
333.070169 -4.113658982050E+03
343.259302 -4.113656548601E+03
353.634103 -4.113649708604E+03
+++++++ FITTING USING ALL POINTS +++++++

The QHA-output looks like this:

LINEAR THERMAL EXPANSION OF CONVENTIONAL LATTICE PARAMETERS

T (K)    a (Ang)    ALPHA_a (1/K)   b (Ang)    ALPHA_b (1/K)   c (Ang)    ALPHA_c (1/K)
20.00   7.39882492   0.32828E-06   7.59681960   0.71307E-06   6.80869752   0.62279E-06
95.56   7.39878526   0.31695E-06   7.59673118   0.68852E-06   6.80862837   0.60167E-06

171.11 7.39919194 0.10446E-05 7.59763816 0.22691E-05 6.80933828 0.19836E-05

The QHA input looks like this:
EXTERNAL
QHA
TEMPERAT
10 20 700
END

And the initial input for the geometry optimization looks like this (this one is even triclinic):
CRYSTAL
0 0 0
2
7.3769 7.6793 6.9013 106.3830 112.3550 99.0830
13
40 0.00000 0.00000 0.00000
19 1.29314 1.19129 0.70840
14 1.18689 0.74146 0.30932
14 0.83411 0.37735 0.15081
14 0.50179 0.31904 0.31345
8 1.38739 0.80941 0.55289
8 1.25595 0.64695 0.11554
8 1.10769 0.91837 0.27965
8 1.00922 0.58169 0.30189
8 0.91191 0.20221 0.18425
8 0.64290 0.40138 0.20756
8 0.28164 0.19499 0.11583
8 0.50000 0.50000 0.50000
OPTGEOM
FULLOPTG
TOLDEX
6.000000E-04
TOLDEG
3.000000E-04
TOLDEE
1.000000E-10
ENDOPT

Thank you again for your advise and time!
Best regards,
Georg

Dear crystal-experts,

I have carried out a lattice dynamics calculation within QHA and I am impressed with crystal23.

However, my crystal strcture is monoclinic, and it seems to me that the EOS calculation prior to QHA is carried out optimizing a,b,c but not the one free angle. As if it had been written not for the most general case, but for orthogonal cases only.

Do I understand this correct?
If so, is there a way how to "switch on" full monoclinic optimization?

Thank you!
Kind regards,
Georg Spiekermann