title test energy conservation with vastly optically thick dust, sphere geometry
c
c commands controlling continuum =========
black 500 STE
c
c commands for density & abundances =========
init "honly.ini"
hden 3.25 -2
grains ism single graphite 
c
c commands controlling geometry  =========
radius from 21 to 26
* stop Av 1000
sphere 
stop temperature 100K
c
c other commands for details     =========
iterate
constant temper 500 K
no grain gas collisional energy exchange
no grain electrons 
no molecules 
cosmic rays background  -10
c
c commands controlling output    =========
save grain temperature "grains_conserve_sp.grntem"
save overview "grains_conserve_sp.ovr"
save dr "grains_conserve_sp.dr"
save continuum units microns "grains_conserve_sp.con"
c
c commands giving the monitors    =========
monitor Tu 1.5811 K linear error 0.02
c
c grains_conserve_sp.in
c class limit 
c ========================================
c 

This tests that multiple absorption / reemission by dust conserves energy
in a spherical geometry.
Radiation density temperature in last zone should be 500 * sqrt(1e21/1e26) = 1.5811 K