search

RMGDFT / rmgdft

RMG is an Open Source code for electronic structure calculations and modeling of materials and molecules. It is based on density functional theory and uses a real space basis and pseudopotentials.
GNU General Public License v2.0
47 stars 11 forks source link

Are there plans to implement the stress tensor? #40

Closed prckent closed 1 year ago

prckent commented 5 years ago

To increase utilization of RMG, I think availability of a stress tensor is very important and is perhaps the most important missing feature for general applications. Are there plans to implement stress or any particular difficulties in the implementation ? The stress tensor would enable easy volume and shape relaxation in solid state calculations, plus NPT molecular dynamics. It is also a helpful check on calculations to catch mistakes such unit conversion errors that are easily made when getting started with a code.

elbriggs commented 5 years ago

We intend to do this but have not determined any sort of timetable for it. No conceptual difficulties just a matter of doing all of the necessary work.

WenchangLu commented 5 years ago

stress tensor calculation has been implemented for cubic, orthorhombic, and hexagonal lattice type. Relaxing the unit cell is in still not implemented. Also extra terms for ultra-soft pseudopotential are not yet implemented.

prckent commented 5 years ago

Thanks! Does it work with self-consistent vdw? i.e. All the plumbing is there for different functionals?

WenchangLu commented 5 years ago

Works only for LDA now. extra terms are needed for vdw, GGA, Ultrasoft pseudopotential, LDA+U.

prckent commented 5 years ago

Does it abort for xc!=lda and unsupported potentials?

WenchangLu commented 5 years ago

No, I will put an condition to abort for stress so that we don't get confused result.

WenchangLu commented 5 years ago

added condition to abort for not-implemented cases.

prckent commented 5 years ago

We had (have) this problem in QMCPACK...

WenchangLu commented 5 years ago

Now stress tensor calculation and cell relax are implemented in norm-conserving and ultrasoft, LDA and GGA. It tested with orthorhombic and hexagonal lattice. vdw-df term for stress is still missing.

WenchangLu commented 4 years ago

Now the code has option for LDA+U and hybrid functionals, stress terms from LDA+U and Exx should be added.