hex 2spec (Hen@X2-->spectrum) is a software package designed to calculate the vib-rotational Raman spectrum of a homonuclear diatomic molecule immersed in a helium cluster. The two-photons Raman process can be summarized as follows:
The first photon with energy polarizes the system, inducing an electric dipole that allows the interaction with the electromagnetic radiation. Afterward, the system is excited to an intermediate state that eventually decays to a final state
through the emission of a photon with energy
. Additionally, due to the system is weakly bonded, the absorbed energy can be enough to dissociate the aggregate following a process called "Vibrational Predissociation" which is directly related with the width of the bands in the final spectra.
To study this process the program uses the following system of coordinates:
The intensity of the absorption line with energy
in resonance with the transition
is be written as
(
details in
M. P. de Lara–Castells et al., AIP Conf. Proc. 1642, 69-80 (2015),
M. P. de Lara–Castells et al., J. Chem. Phys. 132, 194313 (2010)],
N. F. Aguirre et al., Phys. Chem. Chem. Phys 15, 10126 (2013)
):
- Nestor F. Aguirre ( [email protected] )
- Maria P. de Lara-Castells ( [email protected] )
To cite the code, please proceed as follows:
$ HenX2Spec
Usage:
$ HenX2_spec iFile T Jmax [JS] [JL] [LS] | [ALL]
First parameter is the input file, the second one is the temperature to be used to calculate the spectrum, and the third one is the maximum value of the angular momentum J to be considered. The other three parameters are optional and they allow to include the different kind of couplings. By default, the program will include ALL couplings.
Consider the following input file:
$ cat bosN4.inp
STATES 8
# id S Lambda L^2 E Gamma
1a 0.0 0 32.48 -64.49 2e-4 g+
1b 0.0 0 28.06 -64.16 2e-4 g+
2a 0.0 3 42.36 -63.66 2e-4 u
2b 0.0 1 40.00 -63.34 2e-4 u
3a 0.0 4 43.65 -62.76 2e-4 g
4a 0.0 0 33.33 -64.55 2e-4 u+
5a 0.0 3 42.89 -63.73 2e-4 g
6a 0.0 2 37.21 -63.11 2e-4 u
LCOUPLINGS 6
# id1 id2 <id1|L+/-|id2>
1a 5b -0.03006
1b 5b 0.03877
2a 6a -0.02100
2b 4a 0.02500
2b 6a -0.03500
3a 5a 0.06390
SPECTRUM
EMIN -2.0
EMAX 8.0
ESTEP 0.001
DIATOMIC
RE 1.9879
WE 559.72
WEXE 2.675
RMASS 17.71285
POLA 30.91 7.05 1.73 -2.17
POLB 16.83 12.52 5.49 -4.50
This file contains:
- List of the FCI-NO
- List of the couplings
- Parameters to render the spectrum
- Parameters of the Morse potential that represents the diatomic molecule X2
By executing the command
$ HenX2_spec bosN4.inp 0.5 3 ALL > bosN4.out
the program will calculate the pure states for v=0
PURE STATES ( nu = 0 )
======================
Upper primitive state = 6a
Energy Weight
------ ------
J = 0.0
1 -57.42254 0.65472 0.20E-03 <1b(0,0.0)^1\Sigma+(0.0,0.0)g+|
2 -56.69126 0.07983 0.20E-03 <1a(0,0.0)^1\Sigma+(0.0,0.0)g+|
3 -56.54717 0.05274 0.20E-03 <4a(0,0.0)^1\Sigma+(0.0,0.0)u+|
J = 1.0
1 -56.94233 0.16441 0.20E-03 <1b(0,1.0)^1\Sigma+(0.0,0.0)g+|
2 -56.21105 0.02005 0.20E-03 <1a(0,1.0)^1\Sigma+(0.0,0.0)g+|
3 -56.06695 0.01324 0.20E-03 <4a(0,1.0)^1\Sigma+(0.0,0.0)u+|
4 -53.73564 0.00002 0.20E-03 <2b(0,1.0)^1\Pi-(-1.0,0.0)u|
5 -53.73564 0.00002 0.20E-03 <2b(0,1.0)^1\Pi+(1.0,0.0)u|
The notation used to represent the states is as follows:
<1b(0,0.0)^1\Sigma+(0.0,0.0)g+|
^ ^ ^ ^ ^
| | | | |
nu | | Omega |
| | |
J | Sigma
|
2S+1
The following fragment of the output file shows the allowed transitions among vib-rotational pure states
Transitions among pure states
=============================
Initial State End State dE I Gamma Type
------------- --------- -- - ----- ----
<1a(0,0.0)^1\Sigma+(0.0,0.0)g+|
<1a(1,0.0)^1\Sigma+(0.0,0.0)g+| -0.047243 0.024247 0.20E-03 Q
<1a(1,2.0)^1\Sigma+(0.0,0.0)g+| 1.384683 0.006855 0.20E-03 S
The following commands can be used to visualize both the energetic levels and the vib-rotational Raman spectrum:
$ HenX2Spec_plotSpectra -i bosN4.inp -p -y 5000 -r -0.07 -0.02
$ HenX2Spec_plotStates bosN4.inp
