Rovibrational spectra of ammonia. I. Unprecedented accuracy of a potential energy surface used with nonadiabatic corrections

被引:102
作者
Huang, Xinchuan [2 ]
Schwenke, David W. [1 ]
Lee, Timothy J. [1 ]
机构
[1] NASA, Ames Res Ctr, Moffett Field, CA 94035 USA
[2] SETI Inst, Mountain View, CA 94043 USA
关键词
ELECTRONIC GROUND-STATE; MU-M REGION; (NH3)-N-14; NH3; SPECTROSCOPY; TRANSITIONS; INTENSITIES; TERAHERTZ; BANDS; WATER;
D O I
10.1063/1.3541351
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
In this work, we build upon our previous work on the theoretical spectroscopy of ammonia, NH3. Compared to our 2008 study, we include more physics in our rovibrational calculations and more experimental data in the refinement procedure, and these enable us to produce a potential energy surface (PES) of unprecedented accuracy. We call this the HSL-2 PES. The additional physics we include is a second-order correction for the breakdown of the Born-Oppenheimer approximation, and we find it to be critical for improved results. By including experimental data for higher rotational levels in the refinement procedure, we were able to greatly reduce our systematic errors for the rotational dependence of our predictions. These additions together lead to a significantly improved total angular momentum (J) dependence in our computed rovibrational energies. The root-mean-square error between our predictions using the HSL-2 PES and the reliable energy levels from the HITRAN database for J = 0-6 and J = 7/8 for (NH3)-N-14 is only 0.015 cm(-1) and 0.020/0.023 cm(-1), respectively. The root-mean-square errors for the characteristic inversion splittings are approximately 1/3 smaller than those for energy levels. The root-mean-square error for the 6002 J = 0-8 transition energies is 0.020 cm(-1). Overall, for J = 0-8, the spectroscopic data computed with HSL-2 is roughly an order of magnitude more accurate relative to our previous best ammonia PES (denoted HSL-1). These impressive numbers are eclipsed only by the root-mean-square error between our predictions for purely rotational transition energies of (NH3)-N-15 and the highly accurate Cologne database (CDMS): 0.00034 cm(-1) (10 MHz), in other words, 2 orders of magnitude smaller. In addition, we identify a deficiency in the (NH3)-N-15 energy levels determined from a model of the experimental data. (C) 2011 American Institute of Physics. [doi:10.1063/1.3541351]
引用
收藏
页数:15
相关论文
共 29 条
[1]   Cavity-enhanced absorption spectroscopy of the 1.5 μm band system of jet-cooled ammonia [J].
Berden, G ;
Peeters, R ;
Meijer, G .
CHEMICAL PHYSICS LETTERS, 1999, 307 (3-4) :131-138
[2]   Measurements of 14NH3 in the ν2=1 state by a solid-state, photomixing, THz spectrometer, and a simultaneous analysis of the microwave, terahertz, and infrared transitions between the ground and ν2 inversion-rotation levels [J].
Chen, P ;
Pearson, JC ;
Pickett, HM ;
Matsuura, S ;
Blake, GA .
JOURNAL OF MOLECULAR SPECTROSCOPY, 2006, 236 (01) :116-126
[3]   Rovibrational spectra of ammonia. II. Detailed analysis, comparison, and prediction of spectroscopic assignments for 14NH3, 15NH3, and 14ND3 [J].
Huang, Xinchuan ;
Schwenke, David W. ;
Lee, Timothy J. .
JOURNAL OF CHEMICAL PHYSICS, 2011, 134 (04)
[4]   A procedure for computing accurate ab initio quartic force fields:: Application to HO2+ and H2O [J].
Huang, Xinchuan ;
Lee, Timothy J. .
JOURNAL OF CHEMICAL PHYSICS, 2008, 129 (04)
[5]   NH3 and PH3 line parameters:: the 2000 HITRAN update and new results [J].
Kleiner, I ;
Tarrago, G ;
Cottaz, C ;
Sagui, L ;
Brown, LR ;
Poynter, RL ;
Pickett, HM ;
Chen, P ;
Pearson, JC ;
Sams, RL ;
Blake, GA ;
Matsuura, S ;
Nemtchinov, V ;
Varanasi, P ;
Fusina, L ;
Di Lonardo, G .
JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER, 2003, 82 (1-4) :293-312
[6]  
Lee T.J., 1995, Quantum Mechanical Electronic Structure Calculations with Chemical Accuracy
[7]   New VISTA on ammonia in the 1.5 μm region:: Assignments for the ν3+2ν4 bands of 14NH3 and 15NH3 by isotopic shift labeling [J].
Lees, R. M. ;
Li, Li ;
Xu, Li-Hong .
JOURNAL OF MOLECULAR SPECTROSCOPY, 2008, 251 (1-2) :241-251
[8]   External cavity tunable diode laser spectrum of the v1+v3 N-H stretching combination band of 15NH3 [J].
Lees, R. M. ;
Li, Li ;
Liu, Zhengfeng ;
Xu, Li-Hong .
JOURNAL OF MOLECULAR STRUCTURE, 2006, 795 (1-3) :134-142
[9]   The vibrational levels of ammonia [J].
Léonard, C ;
Handy, NC ;
Carter, S ;
Bowman, JM .
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 2002, 58 (04) :825-838
[10]   External cavity tunable diode laser spectra of the v1+2v4 stretch-bend combination bands of 14NH3 and 15NH3 [J].
Li, Li ;
Lees, R. M. ;
Xu, Li-Hong .
JOURNAL OF MOLECULAR SPECTROSCOPY, 2007, 243 (02) :219-226