First‐principles simulation of the UV absorption spectrum of ketene

Nooijen, Marcel

doi:10.1002/qua.10724

Cited by 47 publications

(40 citation statements)

References 44 publications

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“…As is done in Ref. 18 the overlap matrix S AO is approximated by the corresponding overlap matrix for the equilibrium structure, since the displacements from the equilibrium structure are very small. The transformation matrix is then determined in such a way that the corresponding diabatic overlap matrix is almost diagonal,…”

Section: ͑6͒mentioning

confidence: 99%

“…A diabatizing scheme following Ref. 18 is applied to obtain a Taylor-series expansion of an effective Hamiltonian in a diabatic basis, from which diabatic potential energy curves can be obtained. This effective Hamiltonian is also used to calculate the fine structure of the electronic absorption spectrum of N 2 , including the vibronic couplings between the diabatic model potential energy curves for the 1 ⌺ u ϩ states, and separately for the 1 ⌸ u states.…”

Section: Introductionmentioning

confidence: 99%

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Vibronic coupling and double excitations in linear response time-dependent density functional calculations: Dipole-allowed states of N2

Neugebauer

Baerends

Nooijen

2004

The Journal of Chemical Physics

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The present study serves two purposes. First, we evaluate the ability of present time-dependent density functional response theory ͑TDDFRT͒ methods to deal with avoided crossings, i.e., vibronic coupling effects. In the second place, taking the vibronic coupling effects into account enables us, by comparison to the configuration analysis in a recent ab initio study ͓J. Chem. Phys. 115, 6438 ͑2001͔͒, to identify the neglect of double excitations as the prime cause of limited accuracy of these linear response based TDDFRT calculations for specific states. The ''statistical averaging of ͑model͒ orbital potentials ͑SAOP͒'' Kohn-Sham potential is used together with the standard adiabatic local-density approximation ͑ALDA͒ for the exchange-correlation kernel. We use the N 2 molecule as prototype, since the TDDFRT/SAOP calculations have already been shown to be accurate for the vertical excitations, while this molecule has a well-studied, intricate vibronic structure as well as significant double excitation nature in the lowest 1 ⌸ u state at elongated bond lengths. A simple diabatizing scheme is employed to obtain a diabatic potential energy matrix, from which we obtain the absorption spectrum of N 2 including vibronic coupling effects. Considering the six lowest dipole allowed transitions of 1 ⌺ u ϩ and 1 ⌸ u symmetry, we observe a good general agreement and conclude that avoided crossings and vibronic coupling can indeed be treated satisfactorily on the basis of TDDFRT excitation energies. However, there is one state for which the accuracy of TDDFRT/ ALDA clearly breaks down. This is the state for which the ab initio calculations find significant double excitation character. To deal with double excitation character is an important challenge for time-dependent density functional theory.

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Section: ͑6͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vibronic coupling and double excitations in linear response time-dependent density functional calculations: Dipole-allowed states of N2

Neugebauer

Baerends

Nooijen

2004

The Journal of Chemical Physics

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“…This difference, as well as the relation between FSCC and STEOM-CC, is discussed in Appendix C. Subtracting the Schrödinger equation for the ground state [Eq. (32)] multiplied from the left by R n :…”

Section: A Tid Formalism: Steom-ccmentioning

confidence: 99%

“…STEOM-CC introduced by Nooijen and Bartlett 19,20 is an effective and accurate method for calculating transition energies. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] STEOM-CC can be viewed as an intermediate approach between FSCC [37][38][39][40][41][42][43][44] and equation-of-motion coupled cluster (EOM-CC). [45][46][47][48][49] The starting point of these three TID schemes [ Fig.…”

Section: Introductionmentioning

confidence: 99%

Similarity transformed coupled cluster response (ST-CCR) theory - A time-dependent similarity transformed equation-of-motion coupled cluster (STEOM-CC) approach

Landau

2013

The Journal of Chemical Physics

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This paper presents a new method for calculating spectroscopic properties in the framework of response theory utilizing a sequence of similarity transformations (STs). The STs are preformed using the coupled cluster (CC) and Fock-space coupled cluster operators. The linear and quadratic response functions of the new similarity transformed CC response (ST-CCR) method are derived. The poles of the linear response yield excitation-energy (EE) expressions identical to the ones in the similarity transformed equation-of-motion coupled cluster (STEOM-CC) approach. ST-CCR and STEOM-CC complement each other, in analogy to the complementarity of CC response (CCR) and equation-of-motion coupled cluster (EOM-CC). ST-CCR/STEOM-CC and CCR/EOM-CC yield size-extensive and size-intensive EEs, respectively. Other electronic-properties, e.g., transition dipole strengths, are also size-extensive within ST-CCR, in contrast to STEOM-CC. Moreover, analysis suggests that in comparison with CCR, the ST-CCR expressions may be confined to a smaller subspace, however, the precise scope of the truncation can only be determined numerically. In addition, reformulation of the time-independent STEOM-CC using the same parameterization as in ST-CCR, as well as an efficient truncation scheme, is presented. The shown convergence of the time-dependent and time-independent expressions displays the completeness of the presented formalism.

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“…7,[12][13][14]25 In KDC theory, the computation of the photoelectron spectrum proceeds in two steps. In this presentation we use the language of negative ion photodetachment, although the approach is also suitable for photoionization.…”

Section: Improved Algorithms For Kdc Theorymentioning

confidence: 99%

From Ignition to Photoelectron Spectroscopy Conical Intersection Impact the Study of Energetic Materials

Yarkony¹

2012

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First‐principles simulation of the UV absorption spectrum of ketene

Cited by 47 publications

References 44 publications

Vibronic coupling and double excitations in linear response time-dependent density functional calculations: Dipole-allowed states of N2

Vibronic coupling and double excitations in linear response time-dependent density functional calculations: Dipole-allowed states of N2

Similarity transformed coupled cluster response (ST-CCR) theory - A time-dependent similarity transformed equation-of-motion coupled cluster (STEOM-CC) approach

From Ignition to Photoelectron Spectroscopy Conical Intersection Impact the Study of Energetic Materials

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