TY  - RPRT
TI  - Simple formula for the atomic forces in the augmented-plane-wave method.
AU  - JM Soler
AU  - AR Williams
PY  - 1989
DO  - 10.1103/physrevb.40.1560
UR  - https://pubmed.ncbi.nlm.nih.gov/9992009/
ID  - 9992009
ER  -