Ab initio calculations on the and states of AlNC and simulation of the AlNC - emission spectra

Geometry optimization and harmonic vibrational frequencies calculations were carried out on the and states of AlNC, employing a variety of ab initio molecular orbital methods, including the SERHF, CIS, MP2, and QCISD methods, with basis sets up to the size of the cc-pVQZ basis set. In addition, single-point energy calculations at the CCSD(T) and CASSCF/MRCI levels were performed to determine the transition energy (Te) between the two electronic states. Franck–Condon calculations were carried out for the – electronic transition, employing ab initio force constants and optimized geometries. The dispersed fluorescence spectra arising from the (0,0,0), (0,0,1), and (0,0,2) single vibrational levels (SVL) of the upper state were simulated using the computed Franck–Condon factors. Based on the computed Te (36896 cm−1 at the CASSCF/MRCI/cc-pVTZ level) and the simulated emission spectra, the band system observed at 36389 cm−1 by Gerasimov et al. [ J Chem Phys 110, 220 (1999)] has been assigned to the AlNC – transition. A systematic variation of the state geometrical parameters was carried out in an iterative Franck–Condon analysis (IFCA) treatment of the SVL emission, with the geometry of the ground state being fixed to the available experimental geometry. The best match between the simulated and observed spectra gave the first experimentally derived geometry of the state (Al–N=1.785±0.005 A and N–C=1.150±0.008 A). © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1896–1906, 2001

[1]  Edmond P. F. Lee,et al.  Simulation of photoelectron and electronic spectra of small molecules , 2000 .

[2]  D. Bounds,et al.  An ab initio molecular orbital study of NaCN and KCN , 1981 .

[3]  H. Schaefer,et al.  Spectroscopic constants and potential energy surfaces for the possible interstellar molecules A1NC and A1CN , 1995 .

[4]  R. Levine.  Molecular reaction dynamics , 2005 .

[5]  M. Fukushima.  LASER INDUCED FLUORESCENCE SPECTROSCOPY OF ALNC/ALCN IN SUPERSONIC FREE EXPANSIONS , 1998 .

[6]  Paul von Ragué Schleyer,et al.  The structures of LiNC, NaNC, and KNC: Potential energy surface for the orbiting motion of the metal cation around the CN group , 1994, J. Comput. Chem..

[7]  T. Phillips,et al.  Exotic fluoride molecules in IRC +10216: Confirmation of AlF and searches for MgF and CaF , 1994 .

[8]  J. Robinson,et al.  The millimeter-wave spectrum of AlNC: chemical trends in metal isocyanide molecules , 1997 .

[9]  P. Mukherjee,et al.  Theoretical study on the quasi-bound state and UV spectrum of H2O2 with inclusion of the vibrational structure , 1994 .

[10]  Xin Yang,et al.  Laser fluorescence excitation spectra of the AlNC and AlCN isomers , 1999 .

[11]  M. Yamaguchi,et al.  Vibrational analysis and calculation of Franck–Condon factors for the vinoxy radical X̃(2A‘) and B̃(2A‘) states , 1990 .

[12]  W. C. Lineberger,et al.  AN EXPERIMENTAL STUDY OF THE LOW-LYING ELECTRONIC STATES OF WO2 , 1999 .

[13]  Yit‐Tsong Chen,et al.  On the theoretical investigation of vibronic spectra of ethylene by ab initio calculations of the Franck–Condon factors , 1996 .

[14]  K. Kawaguchi,et al.  Laboratory Spectroscopy of MgNC: The First Radioastronomical Identification of Mg-bearing Molecule , 1993 .

[15]  J. Cernicharo,et al.  Detection of MgCN in IRC +10216: A New Metal-bearing Free Radical , 1995 .

[16]  J. Carlier,et al.  Spectre de photoélectrons et calcul des facteurs de franck-condon pour H2O, D2O, HDO , 1977 .

[17]  M. Yamaguchi,et al.  Electronic structure of vinylthio radical (CH2CHS): A theoretical study , 1990 .

[18]  Edmond P. F. Lee,et al.  Franck–Condon analysis of photoelectron and electronic spectra of small molecules , 1998 .

[19]  Edmond P. F. Lee,et al.  Simulation of Emission Spectra of the PF2 (2B2 → X2B1) Transition by ab Initio Calculation and Franck−Condon Analysis , 1996 .