1 2! Unit cell optimisation for Ge with the PBE functional. This is performed with 3! geometric optimisation in which the lattice vectors are changed. 4 5! Setting 'latvopt' to 1 performs full unconstrained optimisation of the lattice 6! vectors. Setting it to 2 results in an iso-volumetric optimisation. In both 7! cases, the atomic positions are also optimised. To constrain the atomic 8! positions, set the nuclear mass to be a negative number in the species file. 9 10! As the calculation progresses, you can plot the files TOTENERGY_OPT.OUT and 11! STRESSMAX.OUT to see the change in the total energy and stress tensor. The 12! modulus of the maximum force on the atoms is written to FORCEMAX.OUT. 13 14! The updated unit cell geometry is written to GEOMETRY_OPT.OUT. The last entry 15! in this file contains the final lattice parameters and atomic positions. 16 17tasks 18 2 19 20! unconstrained optimisation of the lattice vectors 21latvopt 22 1 23 24mixtype 25 3 26 27! switch on high-quality parameters for accurate stress tensors 28highq 29 .true. 30 31! switch off automatic determination of the k-point grid 32autokpt 33 .false. 34 35ngridk 36 4 4 4 37 38! PBE exchange-correlation functional 39xctype 40 20 41 42avec 43 1.0 1.0 0.0 44 1.0 0.0 1.0 45 0.0 1.0 1.0 46 47scale 48 5.3451 49 50sppath 51 '../../../species/' 52 53atoms 54 1 : nspecies 55 'Ge.in' : spfname 56 2 : natoms; atposl below 57 0.0 0.0 0.0 58 0.25 0.25 0.25 59 60