Analytic gradients for excited states in the coupled-cluster model CC2 employing the resolution-of-the-identity approximation

2003 ◽  
Vol 119 (10) ◽  
pp. 5021-5036 ◽  
Author(s):  
Andreas Köhn ◽  
Christof Hättig
Keyword(s):  
Excited States ◽  
Cluster Model ◽  
Coupled Cluster ◽  
Resolution Of The Identity

Large scale polarizability calculations using the approximate coupled cluster model CC2 and MP2 combined with the resolution-of-the-identity approximation

2012 ◽  
Vol 136 (17) ◽  
pp. 174106 ◽  
Author(s):  
Daniel H. Friese ◽  
Nina O. C. Winter ◽  
Patrick Balzerowski ◽  
Raffael Schwan ◽  
Christof Hättig
Keyword(s):  
Cluster Model ◽  
Large Scale ◽  
Coupled Cluster ◽  
Resolution Of The Identity

Inclusion of the (T) triples correction into the linear-r12 corrected coupled-cluster model CCSD(R12)

2006 ◽  
Vol 106 (11) ◽  
pp. 2306-2317 ◽  
Author(s):  
Heike Fliegl ◽  
Christof Hättig ◽  
Wim Klopper
Keyword(s):  
Cluster Model ◽  
Coupled Cluster

scholarly journals Theoretical Electronic and Rovibrational Studies for Anions of Interest to the DIBs

2013 ◽  
Vol 9 (S297) ◽  
pp. 344-348 ◽  
Author(s):  
R. C. Fortenberry
Keyword(s):  
Excited State ◽  
Excited States ◽  
State Of The Art ◽  
Spectroscopic Constants ◽  
Coupled Cluster ◽  
Electronic Excitations ◽  
Electronically Excited States ◽  
Coupled Cluster Theory ◽  
Electronically Excited ◽  
Enolate Anion

AbstractThe dipole-bound excited state of the methylene nitrile anion (CH2CN−) has been suggested as a candidate carrier for a diffuse interstellar band (DIB) at 803.8 nm. Its corresponding radical has been detected in the interstellar medium (ISM), making the existence for the anion possible. This work applies state-of-the-art ab initio methods such as coupled cluster theory to reproduce accurately the electronic excitations for CH2CN− and the similar methylene enolate anion, CH2CHO−. This same approach has been employed to indicate that 19 other anions may possess electronically excited states, five of which are valence in nature. Concurrently, in order to assist in the detection of these anions in the ISM, work has also been directed towards predicting vibrational frequencies and spectroscopic constants for these anions through the use of quartic force fields (QFFs). Theoretical rovibrational work on anions has thus far included studies of CH2CN−, C3H−, and is currently ongoing for similar systems.

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