The compute gkma keyword
compute_gkma keyword is used to calculate the modal heat current using the Green-Kubo Modal Analysis (GKMA) method [Lv 2016].
compute_gkma sample_interval first_mode last_mode bin_option size
sample_intervalis the sampling interval (in number of steps) used to compute the heat modal heat current.
first_modeis the first mode in the eigenvector.in file to include in the calculation.
last_modeis the last mode in the eigenvector.in file to include in the calculation.
bin_optiondetermines which binning technique to use:
sizedefines how the modes are added to each bin. If
bin_size, then this is an integer describing how many modes are included per bin. If
f_bin_size, then binning is by frequency and this is a float describing the bin size in THz.
compute_gkma 10 1 27216 f_bin_size 1.0
This means that (1) you want to calculate the modal heat current with the GKMA method; (2) the modal heat flux will be sampled every 10 steps; (3) the range of modes you want to include of calculations are from 1 to 27216; (4) you want to bin the modes by frequency with a bin size of 1 THz.
compute_gkma 10 1 27216 bin_size 1
This example is identical to Example 1, except the modes are binned by count. Here, each bin only has one mode (i.e. all modes are output).
compute_gkma 10 1 27216 bin_size 10
This example is identical to Example 2, except each bin has 10 modes.
- This computation can be very memory intensive. The memory requirements are comparable to the size of the eigenvector.in file.
- Depending number of steps run, sampling interval, and number of bins, the heatmode.out output file can become very large as well (i.e. many GBs)
- This keyword cannot be used in the same run as the compute_hnema keyword. The keyword appeared last will be used in the run.
- [Lv 2016] Wei Lv and Asegun Henry, Direct calculation of modal contributions to thermal conductivity via Green-Kubo modal analysis, New J. Phys. 18, 013028 (2016).