Hello!
My case is unexpectedly high calculated unit cell metrics for a fully relaxed model using CASTEP code.
Some technical notes are describing current state:
1)A model of inorganic solid has been developed form quite accurate PXRD data (T = 295 K, wRp 4.4%) and thoroughly checked before
any DFT calculations.
2) hR cell of a=b~5.0, and c =29.5 has been converted to pR and relaxed to 3.7 meV/A and 0.01 GPa of maximal residual force
and 0.01 GPa of stress with "gold standart" GGA/PBE/USPP.
3) While resulting interatomic distances are quite well, computed cell periods are notably larger: a=b~5.4, c~30.2
Assuming an absence of thermal expansion (T = 0 K), how could an elongation could be instead of a cell contraction?
Thank you.
Art
My case is unexpectedly high calculated unit cell metrics for a fully relaxed model using CASTEP code.
Some technical notes are describing current state:
1)A model of inorganic solid has been developed form quite accurate PXRD data (T = 295 K, wRp 4.4%) and thoroughly checked before
any DFT calculations.
2) hR cell of a=b~5.0, and c =29.5 has been converted to pR and relaxed to 3.7 meV/A and 0.01 GPa of maximal residual force
and 0.01 GPa of stress with "gold standart" GGA/PBE/USPP.
3) While resulting interatomic distances are quite well, computed cell periods are notably larger: a=b~5.4, c~30.2
Assuming an absence of thermal expansion (T = 0 K), how could an elongation could be instead of a cell contraction?
Thank you.
Art
