Posts

• ---

  Stability calculations
  undefined aerba

  Formally, if finite temperature effects are to be included, the internal static energy E needs to be substituted with the free energy F in the definition of the Hessian. This is easier said than done. However, for the elastic tensor, we do have an implementation to compute free energy derivatives with respect to lattice strain (i.e. thermo-elasticity). See also:

  https://www.mdpi.com/2075-163X/9/1/16

  The elastic tensor is not defined for 0D systems, where you could just explore the "dynamical stability" in terms of the vibration frequencies.

• ---

  Stability calculations
  undefined aerba

  Hi,

  Stability is a broad concept that can be interpreted and analyzed in many ways. One way to look at it is the following: checking whether or not the Hessian of second energy derivatives is positive-definite (all eigenvalues are positive) or not, i.e. if the structure is a local minimum of the potential energy surface (PES). Indeed if small structural perturbations produce an energy decrease rather than increase (that is if some of the eigenvalues are negative) the structure can not be considered "stable".

  Two types of Hessian matrix can be considered, which correspond to two types of stability:

  • Hessian with respect to atomic displacements within a fixed cell for dynamical (phonon) stability. This corresponds to checking if all harmonic frequencies are positive.

  • Hessian with respect to lattice distortions for mechanical stability (so-called Born stability conditions). This corresponds to checking if all the eigenvalues of the elastic tensor are positive.

  Hope this helps,

• ---

  Creating Wannierization Input Files
  undefined GiacomoAmbrogio

  Hi Chris,
  I tested the same input with properties and it starts correctly, so the input deck itself seems fine. The issue may instead be that the launch script that is not pointing to the correct input file.

  Without your fort.9 I cannot test the full input, but if you share a few details on your setup and how you launch the job, it may be easier to identify the problem.

• ---

  Localized Crystalline Orbitals
  undefined GiacomoAmbrogio

  Dear Chhatra,

  Unfortunately, I am not aware of a direct way to reduce the file size generated by the ORBITAL option in the properties module.

  As a possible workaround, you might consider reducing the system size if feasible. Another option could be to post-process the output to extract only the relevant information before visualization.

  I hope this helps.

• ---

  BETAVIB (Vibrational contribution to the SHG and Electro Optic-Effect)
  undefined aerba

  Hi,

  Could you please share your CRYSTAL output file from the BETAVIB calculation? In case you also computed just the electronic term, could you share those output files as well?

  The first link you give looks broken: 404 page not found.
  Thanks,

• ---

  Localized Crystalline Orbitals
  undefined GiacomoAmbrogio

  Hi Chhatra,
  the last 1 in the second line of the NEWK input

  NEWK
  3 3
  1 1  <--- this one
  67 501
  ...
  

  is the number of printing options to switch on (as stated in the manual).

  Thus, the following line contains the number of the print option (67: eigenvectors of the Fock - see the LPRINT appendix in the manual) and the value of that print option (501: number of vectors to print)

• ---

  Troubles with coordinate system in output using POTC
  undefined GiacomoAmbrogio

  Hi denkos,
  From what I can see in the code, the components are not sorted automatically. CRYSTAL just diagonalizes the EFG tensor and prints the three eigenvalues as AA, BB, CC with their corresponding eigenvectors.

• ---

  Some a problem with the EOS calculation
  undefined GiacomoAmbrogio

  Hi Aleksand,
  We investigated the error you encountered. It was caused by a bug in the EOS option, which has been fixed in CRYSTAL23. Unfortunatly, there is no simple workaround available in CRYSTAL17.

  What I can think about is to manually perform the volume-constrained geometry optimizations in separate runs and then interpolate the results manually.

• ---

  Some a problem with the EOS calculation
  undefined GiacomoAmbrogio

  Hi Aleksand,
  Can you post the full output file? I just want to check in which step the error is generated.

• ---

  MSSC2026 Summer School, 14-18 September 2026, Imperial College, London (UK) “Ab initio Modelling in Solid State Chemistry”
  undefined GiacomoAmbrogio

  The Department of Chemistry and the Thomas Young Centre at Imperial College London and the Theoretical Chemistry Group of the University of Torino , in collaboration with the Computational Materials Science Group of the Science and Technology Facilities Council (STFC), are organising the

  

  MSSC2026 Summer School on

  Ab initio Modelling in Solid State Chemistry

  The School is designed for Master and Ph.D. students, as well as for post-docs and researchers who have an interest in getting or strengthening a background in:

  • ️ Computational Solid State Chemistry
  • 🧠 Physics
  • 🧱 Materials Science
  • Surface- and Nano-Science

  The week-long School consists of morning lectures and afternoon hands-on tutorial sessions, where the formal framework and functionalities of the CRYSTAL electronic structure package will be explored.

  While we strongly encourage in-person participation, we also offer the possibility to attend remotely through streaming of morning lectures and afternoon hands-on tutorials.

  Participants will have the opportunity to present their research at a poster session.

  You can register here!
  Friday 8 May - Deadline for payment of early bird fees.

  See the School website for further details.