Theoretical Investigation of the HOCO radical in the Ground Electronic State

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Submitted on 13 Nov 2012

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Theoretical Investigation of the HOCO radical in the Ground Electronic State

M. Mladenovic

To cite this version:

M. Mladenovic. Theoretical Investigation of the HOCO radical in the Ground Electronic State. The

22nd International Conference on High Resolution Molecular Spectroscopy, Sep 2012, Prague, Czech

Republic. pp.X, 2012. �hal-00751396�

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DVR(+R)+FBR DVR(6)

non-direct product type angular basis

Pl1 m(cos3₁) P

l2 m(cos3₂) eim4

direct product type angular basis

Fn1(3₁) F n2(3₂) cos(m4)

RCCSD(T)/cc-pVQZ PES for HOCO

• 3261 RCCSD(T) /cc-pVQZ points were calculated

• analytical 6D representation with 193 parameters in the bond-distance-bond-angle coordinates r1, r2, r3, 5, 6, 7

V(r1,r2,r3,5,6,7)=8 Cijkl mns1

i

s2 j s3 k (5-5ref)^l(6-6ref)^mcos(n7)

using Morse coordinates for the stretches reference geometry= saddle-point geometry

• standard deviation of the fit was 2.4 cm^-1

-54B5D464

Vibrational and rovibrational (J=0-4) energy levels are obtained by means of computational strategies based on the discrete variable representation [DVR6]

and the (functional+pointwise) coor.

representations [DVR(+R)+FBR] together with contraction schemes resulting from several diagonalization and truncation steps.

Rotational constants computed for the ground vibrational state of trans- HOCO and cis-HOCO are in good agreement with the experimental values.

c-H · OCO

HCO₂ t-H · OCO

t-HO · CO

c-HO · CO

OH+CO

-TS

C_2v-TS OH · · CO

t-HOCO

607 cm-1

H+CO₂

c-HOCO

2150 cm-1 3270 5825

9868 cm-1 bend (~90^o, ~123^o)

bend (~115o, ~160o) r(OH)> ~2.3 ao

Two limiting cases associated with oscillator and rotor spectral patterns are identified for the torsion.

Several adiabatic projection schemes have been employed to characterize the vibrational levels and to study the relevance of the intermode coupling (vibrational mixing).

Numerically exact vibrational transitions

are also presented for the quartic force

fields developed recently for trans-HOCO,

.

Our results help to clear up a large

discrepancy between previously reported

vibrational perturbation theory (VPT)

and vibrational configuration interaction

(VCI) predictions for the torsional

frequency.