title collisionally excited H in LTE limit
c
c commands controlling continuum =========
black body, T = 50000 K
ionization parameter -8
c
c commands for density & abundances =========
// >>chng 06 jul 22, density from 18 to 20, large change in H-like
// collision strengths, now much smaller.  Small densities result in extreme
// unphysical departure coefficients in high n levels, with resulting
// runaway maser.  This simulation is highly contrived to test only n-changing
// collisions
hden = 20
init file="hheonly.ini"
c
c commands controlling geometry  =========
stop lyman optical depth -6
stop zone 1
set dr 0
// >>chng 06 jul 22, add this large change in H-like
// collision strengths, now much smaller.  Small densities result in extreme
// unphysical departure coefficients in high n levels, with resulting
// runaway maser.  This simulation is highly contrived to test only n-changing
// collisions - gas is now more neutral so even fewer collisions occur
// setting high eden gets back to intended test
set eden 20 
c
c other commands for details     =========
no induced processes  (OK) 
atom h-like collisions l-mixing off 
atom he-like collapsed levels 20
atom he-like collisions l-mixing off 
constant temperature = 50000 K
iterate
c
c commands controlling output    =========
print h-like departure coefficients
print h-like populations
print he-like departure coefficients
print populations h-like 
//
save overview "limit_lte_h_t50_coll.ovr"
save performance "limit_lte_h_t50_coll.per"
save monitors "limit_lte_h_t50_coll.asr" last
c
c commands giving the monitors    =========
monitor h-like departure coef hydrogen  value 1 largest = 0.14
// 
// >>chng 02 nov 25, added this
//TODO change assert command so have option to look at only high-n
// assert he-like departure coef helium  value 1.006, largest = 0.14
// >>chng 06 jul 22, from -0.163 to -0.0032, RP update H-like cs, now 
// much smaller, ionization changed - note no coll ion in this sim
// >>chng 06 aug 30, from -0.0032 to -0.592, RP H-like cont lowering
// >>chng 06 dec 22, from -0.5920 to -0.4835, RP H-like cont lowering fix
monitor hydrogen 1 ionization -0.4835
// 
// >>chng 06 jul 22, from -0.500 to -2.207, RP update H-like cs, now 
// much smaller, ionization changed - note no coll ion in this sim
// >>chng 06 aug 30, from -2.207 to -0.129, RP H-like cont lowering
// >>chng 06 dec 22, from -0.129 to -0.1732, RP H-like cont lowering fix
monitor hydrogen 2 ionization -0.1732
// 
// >>chng 02 dec 19, from -0.037 to -0.0161 new he atom
// >>chng 04 jul 03, from -0.0161 to -0.0522, NA update H, CO chem net
// >>chng 06 jul 22, from -0.0522 to -0.0154, RP update H-like cs, now 
// much smaller, ionization changed - note no coll ion in this sim
// >>chng 06 aug 24, turn on coll ionization from -0.0154 to -0.390
monitor helium 1 ionization -0.390
// 
// >>chng 02 apr 29, from -1.302 to -1.091, chng coll dat highlevels hei
// >>chng 02 dec 12, from -1.091 to -1.063, different conv criteria
// >>chng 02 dec 19, from -1.063 to -1.44, new he atom
// >>chng 03 feb 38, from -1.44 to -1.464, better hei coll
// >>chng 03 mar 13, from -1.464 to -2.569, better hei coll splitting
// >>chng 04 apr 17, from -2.569 to -2.460, better mole conv
// >>chng 04 jul 03, from -2.460 to -0.946, NA update H, CO chem net
// >>chng 06 jul 22, from -0.946 to -1.458, RP update H-like cs, now 
// much smaller, ionization changed - note no coll ion in this sim
// >>chng 06 aug 24, from -1.458 to -1.484, RP update H, He-like num lev local
// increase error 
// >>chng 06 aug 24, turn on coll ionization from -1.4844 to -0.227
monitor helium 2 ionization -0.227 error 0.1
// 
c limit_lte_h_t50_coll.in
c class limit 
c ========================================
c 

This checks that the model H atom goes to LTE at high densities. 

chng 06 aug 24, had not included collisional ionization, and so he-like
departure coefficients were very large, around 202.  comments said there
were problems.  turned on collisional ionization, no problems noted

chng 06 jul 22
with RP changes in high-n n-changing collisions the rates are now much
smaller - needed to change density to be far higher and several 
quantities changed.  at lower density (1e18 cm-3) the populations are very
unphysical and runaway maser now occurs.  this is only a homework problem
and intended to only test n-changing collisions.  with higher density
this test is done.