Title:
Tutorial example - IR photo-electron spectrum of hydrogen
First, run 'tRecX' with this input file.
Then compute the photo-electron spectra with 'Spectrum' and the output directory as input
The purpose of this exercise is to explore the calculation of IR spectra
in linear polarization, learn to assess accuracy and convergence
Run times
tRecX with given parameters ~2 min on a decent CPU
Spectrum scales linearly with momentum resolution, e.g. 90 sec at -nR=1000
[TASK] run Spectrum, inspect the spectra obtained by Rc=20
[TASK] perform convergence studies
the initial parameters in this file are adjusted to yield ~ 10% accuracy in much of the spectrum
# Verify by varying:
# Eta-axis (i.e. angular momenta)
# Rn-axis radial basis
# TimePropagation: accuracy
# TimePropagation: cutEnergy
[TASK] move to trunc[25,30]
# caution: discretization must be adjusted to start absorption at 30
# caution: convergence wrt. to all above parameters must be re-checked
you should find that truncation of the Coulomb tail is the most critical of all parameters
# Rc - where to pick up the surface flux
Surface: points
20.
# minimal basis for ~10% good results
# note: sorting the axes this way allows faster code
Axis: name,nCoefficients,lower end, upper end,functions,order
Phi,1
Eta,20,-1,1, assocLegendre{Phi}
Rn,48, 0.,20.,polynomial,12
Rn,30, 20.,Infty,polExp[1.]
Absorption: kind, axis, theta, upper
ECS,Rn,0.3,20.
Operator: hamiltonian='1/2<>-<1><1>'
Operator: interaction='iLaserA0[t]<>'
Operator: expectationValue='<1><1>'
# NOTE: we change to a cos^8 pulse envelope (rather close to a Gaussian)
# the cos^2-shape, while quite popular in the community,
# causes UNPHYISCAL ARTEFACTS (that made it into quite a few publications)
Laser: shape, I(W/cm2), FWHM, lambda(nm)
cos8, 2.e14, 3. OptCyc, 800.
# NOTE:
# we have omitted the begin of time propagation: default is to start at the pulse start (or 0, if no pulse is defined)
TimePropagation: end, print,store,cutEnergy,accuracy
10 OptCyc, 0.25 OptCyc,0.05 au,50,5.e-9
TimePropagation: operatorThreshold=5.e-8