VI/119 High accuracy computed water line list - BT2 (Barber+, 2006)
A high accuracy computed water line list - BT2.
Barber R.J., Tennyson J., Harris G.J., Tolchenov R.N.
<Mon. Not. R. Astron. Soc. 368, 1087 (2006)>
=2006MNRAS.368.1087B 2006MNRAS.368.1087B
ADC_Keywords: Atomic physics
Keywords: water - line list - BT2 - molecular spectra
Abstract:
A computed list of H2O infra-red transition frequencies and
intensities is presented. The list, BT2 was produced using a discrete
variable representation two-step approach for solving the
rotation-vibration nuclear motions. It is the most complete water line
list in existence, comprising over 500 million transitions (65% more
than any other list) and is also the most accurate (over 90% of all
experimental levels are within 0.3cm-1 of the BT2 values). Its
accuracy has been confirmed by extensive testing against astronomical
and laboratory data.
The line list has been used to identify water lines in a variety of
objects including: comets, sunspots, a brown dwarf and the nova-like
object V838 Mon. Comparison of the observed intensities with those
generated by BT2 enables physical values to be derived for these
objects. The line list can also be used to provide an opacity for
models of the atmospheres of M-dwarf stars and assign previously
unknown water lines in laboratory spectra.
Description:
The data are in two parts. The first, the 'Levels File' (levels.dat)
is a list of 221,097 energy levels, ordered by J and symmetry block.
About 25,000 of these energy levels have been labelled with the
appropriate angular momentum (J,Ka,Kc) and vibrational (v1,v2,v3)
quantum numbers. The second part of BT2 is the 'Transitions File'.
This has 505,806,202 entries. Each transition references upper and
lower energy levels in the Levels File and gives the Einstein Aif
coefficient for the transition. In uncompressed form the BT2
Transitions File is 12.6Gb of data. Therefore, in order to facilitate
use of the list, the transitions have been ordered by frequency and
separated into 16 smaller files, each representing a specific
frequency range. These have labels of the form 02750-03500-BT2.txt
where the two five digit numbers represent the lower and upper ends of
the frequency range for that particular file. These files are zipped
and need to be unzipped using the command 'bunzip2 filename'.
In addition to the files containing the actual line list, we have
provided a Fortran program, spectra-BT2.f90 that, when compiled on the
user's computer, will produce an executable file. This will enable the
user to generate emission or absorption spectra from BT2 by specifying
various parameters including: temperature, frequency range, cut-off
intensity and line width. There is also the facility to generate
spectra with full ro-vibrational assignments if required. The method
of using spectra-BT2 is detailed in the 'readme-spectra' file and
there are also examples of a job file and an output file. It is
ESSENTIAL to rename or else set up a symbolic link to the Levels File
as: 'fort.80'. Also, spectra-BT2.f90 expects a single input
transitions file, so if the frequency range required spans more than
one of the frequency-ordered files, these must be concatenated to form
a single file. In any event, it is ESSENTIAL to rename or else set up
a symbolic link to the file containing the transitions as: 'fort.13'
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
00000-00250-BT2.txt 24 17490214 Zipped files of frequency-ordered transitions.
Once unzipped, use as 'fort.13' in spectra-BT2
00250-00500-BT2.txt 24 17022667 00250-00500 frequency-ordered transitions
00500-00750-BT2.txt 24 16530697 00500-00750 frequency-ordered transitions
00750-01000-BT2.txt 24 16098481 00750-01000 frequency-ordered transitions
01000-01500-BT2.txt 24 30866787 01000-01500 frequency-ordered transitions
01500-02000-BT2.txt 24 29161189 01500-02000 frequency-ordered transitions
02000-02250-BT2.txt 24 13954798 02000-02250 frequency-ordered transitions
02250-02750-BT2.txt 24 26727622 02250-02750 frequency-ordered transitions
02750-03500-BT2.txt 24 37249656 02750-03500 frequency-ordered transitions
03500-04500-BT2.txt 24 44635822 03500-04500 frequency-ordered transitions
04500-05500-BT2.txt 24 39325124 04500-05500 frequency-ordered transitions
05500-07000-BT2.txt 24 50083781 05500-07000 frequency-ordered transitions
07000-09000-BT2.txt 24 52289428 07000-09000 frequency-ordered transitions
09000-14000-BT2.txt 24 76679377 09000-14000 frequency-ordered transitions
14000-20000-BT2.txt 24 31640191 14000-20000 frequency-ordered transitions
20000-30000-BT2.txt 24 6050421 20000-30000 frequency-ordered transitions
levels.dat 51 221097 File containing the 221,097 energy levels
(some with ro-vibrational assignments).
Once unzipped, use as 'fort.80' in spectra-BT2
readme-spectra 283 80 Explains possible settings for spec.job file
spectra-BT2.f90 94 1328 Fortran code to be generate the spectra
spec.job 158 8 A sample job file, to be modified as required
(example of 6400-6460cm-1 in epsilon Indi)
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See also:
VI/121 : Energy level list and linelist of HCN/HNC (Harris+, 2006)
VI/127 : High accuracy line list of HDO (Voronin+; 2009)
Byte-by-byte Description of file: *-BT2.txt
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Bytes Format Units Label Explanations
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1- 7 I7 --- Level1 Reference level in Energy Level File
8- 14 I7 --- Level2 Reference level in Energy Level File
15- 24 E10.3 s-1 A Einstein A coefficient
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Byte-by-byte Description of file: levels.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- Level [1,221097] Number of the level
8- 9 I2 --- J [0,50] Total angular momentum quantum number
11 I1 --- Sym [1,4] Symmetry bloc number (1)
13- 16 I4 --- Block Reference in the block
18- 30 F13.6 cm-1 E [0,30000] Energy of the level
32- 34 I3 --- v1 [-2,8] v1 symmetric stretch quantum number
36- 38 I3 --- v2 [-2,17] v2 bend quantum number
40- 42 I3 --- v3 [-2,7] v3 asymmetrics stretch quantum number
44- 45 I2 --- --- J (repeat of bytes 7-9)
47- 48 I2 --- Ka [-2,47] Ka rotational quantum number
50- 51 I2 --- Kc [-2,50] Kc rotational quantum number
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Note (1): Symmetry block numbered as in Table 1 of paper:
---------------------------------------------------------
J parity (even/odd) e e e e o o o o
vibrational basis symmetry (q) e e o o e e o o
rotational parity (p) e o e o e o e o
ortho/para state (O/P) P O O P O P P O
Symmetry Block number (code) 1 3 4 2 3 1 2 4
----------------------------------------------------------
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Contacts:
R.J. Barber, bob(at)theory.phys.ucl.ac.uk
J. Tennyson, j.tennyson(at)ucl.ac.uk
G. J. Harris, greg(at)theory.phys.uc.ac.uk
(End) Bob Barber [Univ. Coll. London] 13-Jan-2006