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Determining minimum energy conical intersections by enveloping the seam: exploring ground and excited state intersections in coupled cluster theory

T0 review · 3 major / 5 minor · reviewed 2026-08-12 · deepseek-v4-flash

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Pith's one-line read Minimizing the upper electronic state on a fixed small energy gap gives accurate minimum-energy conical intersections and lets coupled cluster theory describe ground-state crossings in ethylene, azobenzene, and uracil.

desk verdict Honest, useful tube-algorithm paper for CCSD ground-state ε-MECIs; flat-direction non-uniqueness is a real caveat the authors don't discuss, but the method and S1/S2 validation hold up. read the letter →

arxiv 2411.08207 v2 pith:RB3BZCLW submitted 2024-11-12 physics.chem-ph

Sara Angelico , Eirik F. Kj{o}nstad , Henrik Koch This is my paper · ORCID
classification physics.chem-ph
keywords minimumenergyconicalintersectiontubealgorithmcoupledclustersinglesanddoublesnonadiabaticcoupling-freeoptimizationisosurfacegapsimilarityconstrainedground-statephotochemistry
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

The paper proposes and tests a way to find minimum-energy conical intersections, the geometries where two electronic states are degenerate and population can switch between surfaces, without computing nonadiabatic coupling vectors. Instead of converging onto the crossing seam itself, the algorithm minimizes the upper state's energy on the nearby hypersurface where the two states are separated by a small fixed energy difference, here called the tube. The paper argues that for small enough energy gaps this tube wraps around the seam and its minimum is an accurate stand-in for the true crossing minimum, and that the optimization never touches the degenerate point, so the numerical breakdowns that plague coupled cluster theory near conical intersections are avoided. Using this approach, the paper demonstrates that coupled cluster singles and doubles reproduces multireference and spin-flip TDDFT geometries for ground-state intersections in ethylene, azobenzene, and uracil, suggesting coupled cluster dynamics could describe nonradiative relaxation to the ground state.

What carries the argument

The tube isosurface $I_\varepsilon = \{R : E_m(R) - E_n(R) = \varepsilon\}$ is the central object; it is an $(N-1)$-dimensional hypersurface in energy parallel to the crossing seam, and its limit as $\varepsilon \to 0$ is the seam itself. The work is carried by the modified gradient $G^\varepsilon_{nm} = P^\varepsilon_{nm} \nabla E_m + 2(E_m - E_n - \varepsilon) g^\varepsilon_{nm}/\|g^\varepsilon_{nm}\|$ with $P^\varepsilon_{nm} = 1 - g_{nm} g_{nm}^T$, where $g_{nm} = \nabla(E_n - E_m)$. The first term moves the geometry along the tube to reduce the upper-state energy; the second term drives the geometry onto the tube. Since only $g_{nm}$ is required, no nonadiabatic coupling vectors are needed.

What would settle it

For one ground-state case, take the uracil 6S5 S0/S1 intersection and compute the $\varepsilon$-MECI at a sequence of decreasing $\varepsilon$ down to the coupled cluster convergence limit, while also obtaining a reference MECI with a method that can converge on the seam itself; if the tube minima do not converge to the seam minimum, for instance if the C4C5C6N1 dihedral shifts by more than a few degrees, the central approximation fails for ground states.

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Extended reading notes

Core claim

The paper's central claim is that a minimum-energy conical intersection can be approximated without ever evaluating the crossing seam or nonadiabatic coupling vectors. For two states $m$ and $n$, one fixes a small positive energy $\varepsilon$ and minimizes the upper state's energy on the isosurface $I_\varepsilon = \{R : E_m(R) - E_n(R) = \varepsilon\}$, which for small $\varepsilon$ forms a tube enveloping the seam and collapses onto the seam as $\varepsilon \to 0$. The paper shows that the appropriate modified gradient needs only the energy-difference gradient $g_{nm} = \nabla(E_n - E_m)$, and that the converged $\varepsilon$-MECI geometries approach the gradient-projection MECI for an excited-state crossing in uracil. For ground-state crossings, the paper claims that CCSD $\varepsilon$-MECIs of ethylene, azobenzene, and uracil agree quantitatively with state-averaged CASSCF and spin-flip TDDFT reference structures, which is the first demonstration that coupled cluster theory can describe ground-state conical intersections.

Load-bearing premise

The paper's results depend on the assumption that the finite energy gaps it actually converged to, 0.27 eV for ethylene, 0.20 eV for azobenzene, and 0.07 to 0.14 eV for uracil ground-state crossings, are small enough that the tube minimum is close to the true seam minimum; that limit is demonstrated directly for one excited-state crossing but not for the ground-state crossings.

Editorial extensions

If this is right

  • Coupled cluster singles and doubles can be used, at least for the molecules tested, to locate meaningful S0/S1 conical intersection structures despite its known convergence problems at true degeneracies.
  • The algorithm places no special demand on the electronic structure method: any method with analytic or numerical energy gradients for the two states can use it.
  • Stepwise reduction of $\varepsilon$ gives a practical route to approach the seam from above, with the converged geometry at a larger $\varepsilon$ serving as an initial guess for a smaller $\varepsilon$.
  • If the S0/S1 accuracy holds more generally, coupled cluster theory becomes a candidate for nonadiabatic dynamics simulations that describe nonradiative relaxation to the ground state.
  • The optimization can converge to an avoided crossing rather than a true intersection, and the paper notes that a geometric-phase loop is needed to confirm a genuine conical intersection.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Editorial inference: the drift of the $\varepsilon$-MECI geometry as $\varepsilon$ shrinks could serve as a diagnostic of how close a given electronic structure method is to a genuine degeneracy; a geometry that stabilizes as $\varepsilon \to 0$ signals a converged approximation, while one that keeps shifting signals an avoided crossing or a method artifact.
  • Editorial inference: running surface-hopping or mean-field dynamics on the $I_\varepsilon$ tube with a fixed small $\varepsilon$ might let coupled cluster trajectories avoid the singular region altogether while still sampling the relevant branching-plane topography; this is a testable extension the paper does not pursue.
  • Editorial inference: because the gradient expression applies to any pair of states whose energy gap can be differentiated, the approach could be extended to intersections between other excited states, or to state pairs in multireference methods, without derivative couplings.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 5 minor

Summary. The Letter analyzes an optimization algorithm, called the tube algorithm, for locating minimum energy conical intersections without using nonadiabatic coupling vectors. The method minimizes the energy of the upper state on the isosurface I_ε = {R : E_m(R) - E_n(R) = ε}, using the projected gradient in Eq. (5). The authors validate the algorithm on the S1/S2 intersection in uracil by comparing with the gradient projection method, and then apply it to S0/S1 intersections in ethylene, azobenzene, and uracil at the CCSD level, comparing the resulting ε-MECI geometries with CASSCF and SF-TDDFT reference structures. On this basis they conclude that CCSD, despite its convergence problems at degeneracies, can provide an accurate description of conical intersections with the ground state and may be suitable for nonadiabatic dynamics targeting ground-state relaxation.

Significance. If the tube algorithm is reliable, it is a useful tool because it removes the need for derivative couplings and because it sidesteps coupled-cluster convergence problems near the seam. The paper has clear strengths: the geometric picture of the tube, the open repository of optimized structures, the stepwise ε-reduction protocol, and the S1/S2 uracil comparison against an independent optimizer. However, the central claim that finite-ε CCSD tube minima represent true S0/S1 MECIs is not fully established: for the S0/S1 cases the smallest converged gaps are 0.07–0.27 eV, and the paper gives no proof or systematic ε→0 convergence study for ground-state intersections. The flat-direction degeneracy of the upper-state energy on I_ε makes the branching-plane coordinates of the converged geometry potentially path-dependent, so the agreement with CASSCF structures may be less decisive than presented.

major comments (3)
  1. [Tube algorithm, Eqs. (4)–(6)] For a locally linear conical intersection, the two adiabatic energies in the branching plane are E_{n,m} = E_0(s) ∓ sqrt(g^2 x^2 + h^2 y^2). On the isosurface I_ε the square root is fixed to ε/2, so the upper-state energy E_m = E_0(s) + ε/2 is, to leading order, independent of the branching-plane coordinates (x,y) along the ellipse. The projected gradient in Eq. (5) therefore has no restoring component along that ellipse, and the converged ε-MECI's branching-plane coordinates are determined by the path by which the optimization first reaches I_ε rather than by the true seam. With reported S0/S1 gaps of 0.07–0.27 eV this ellipse is not negligibly small, so discrepancies such as the uracil oop-O C2N3C4O8 angle (94° vs 113°, Fig. 5 and SI Table 2) may reflect this finite-ε ambiguity rather than CCSD error. A concrete test would be to restart the same ε optimization from different initial branching-plane coordinates and report the spread in the converged internal coordinates, or to project the converged ε-MECI onto the seam and compare with a direct MECI optimization.
  2. [ε→0 limit and ground-state convergence] The paper states that 'for sufficiently small ε, the tube folds around the crossing seam' and that the ε-MECI gives 'an accurate approximation to the minimum energy conical intersection,' but no proof or quantitative convergence analysis is provided for the S0/S1 cases. The only direct ε→0 validation is the S1/S2 uracil case (Fig. 2), where ε is reduced to 0.0027 eV with SCCSD. For the ground-state intersections the smallest converged values are 0.07 eV (uracil 6S5), 0.14 eV (uracil oop-O), 0.20 eV (azobenzene), and 0.27 eV (ethylene) (Figs. 3–5 and SI Table 2), and the SI reports that CCSD ground-state equations do not converge for smaller energy gaps. As presented, the concluding claim that CCSD 'can provide an accurate description of conical intersections with the ground state' is therefore not established; the authors should either supply a convergence study or a proof for S0/S1, or explicitly restrict the claim to finite-ε tube minima.
  3. [Comparison with reference geometries] The accuracy assessment relies on comparisons to CASSCF and SF-TDDFT structures computed with different basis sets and active spaces, for example CCSD/cc-pVDZ vs CASSCF(10/8)/6-31G* for uracil and CCSD/6-31G vs 5SA-CASSCF(6/6)/6-31G for azobenzene. This confounds the effect of the tube approximation with method and basis-set differences. A consistency check at a common basis for at least one S0/S1 case would strengthen the claim that the reported geometry differences are dominated by the electronic-structure treatment rather than by the finite-ε tube effect.
minor comments (5)
  1. [Abstract and Introduction] The phrase 'showing that it minimizes the energy on hypersurfaces that envelop the intersection seam' overstates what is demonstrated: the main text gives the projected-gradient construction and numerical evidence, but not a proof that the ε-MECI converges to the true MECI as ε→0.
  2. [References] A few reference formatting issues should be corrected, including 'Bernhard Schlegel, H.' (Ref. 10, should list H. Bernhard Schlegel), 'Chem. Phys. Letters' (Refs. 10 and 28, journal is Chem. Phys. Lett.), and the accented name 'MartÍnez' in Ref. 22.
  3. [Supporting Information, Table 2] The column headers in SI Table 2 interleave CCSD ε values and literature reference columns without clearly marking which ε belongs to which method; a clearer layout (e.g., subheadings 'CCSD' and 'Reference') would help readers verify which geometry is being compared.
  4. [Main text, uracil 6S5 paragraph] The text says the three methods agree with '53° with SF-TDDFT and 52° for CCSD and CASSCF' for the C4C5C6N1 dihedral; SI Table 2 shows 52° only at ε = 0.07 eV, with 50° and 51° at larger ε, so the ε dependence of the comparison should be stated explicitly.
  5. [Section on S1/S2 uracil] The stepwise procedure is described as starting with CCSD at ε = 0.14 eV and switching to SCCSD for ε ≤ 0.014 eV, while Fig. 2 shows CCSD also at ε = 0.027 eV; the text and figure caption should be harmonized to avoid confusion about which method was used at each ε.

Circularity Check

0 steps flagged · score 1.0 of 10

No significant circularity: the tube-algorithm results are validated against independent literature structures and against the gradient projection method, and the ε-MECI geometries are not fitted to the reference data.

full rationale

The central derivation is self-contained rather than circular. The objective in Eq. (5) is obtained directly from the definition of the isosurface I_ε = {R : E_m(R) − E_n(R) = ε} in Eq. (4), together with the geometric picture of the double cone and the tube it forms along the seam; no parameter is fitted to the CASSCF or SF-TDDFT reference structures. The reported ε values are selected for convergence, not to match the references, and the S1/S2 uracil case is checked in the ε → 0 limit by comparison with the gradient projection method, which is a genuinely different optimizer. The ground-state comparisons use independent literature geometries, and SI Table 2 shows that the uracil structures are essentially unchanged as ε decreases from 0.27 eV to 0.07 eV, so the comparison does not rely on a single conveniently chosen ε. Self-citations to similarity-constrained coupled cluster theory and to geometric-phase failure mechanisms (Refs. 23–27 and 31) provide context, but the core claim that the tube algorithm approximates the MECI and that CCSD gives reasonable ground-state intersection geometries does not reduce to any of those citations. The finite-ε approximation and the possible flat direction of the upper-state energy along the I_ε ellipse in a linear cone are accuracy and representativeness assumptions, not circular reductions: they question whether the converged geometry represents the true MECI, but they do not make the calculation equivalent to its inputs. There is therefore no circularity, and the low score reflects only minor contextual self-citations that are not load-bearing.

Assumptions & free parameters 1 free parameters · 5 assumptions · 0 invented entities

The central algorithm depends on the regularity of the crossing seam, the double-cone topography of the intersection, and the unproved convergence of the ε-constrained minimum to the true MECI as ε to 0. The only adjustable input is the energy gap ε, which is not fitted to the reference structures; stability across ε values is shown for uracil. No new physical entities are introduced.

free parameters (1)
  • epsilon (energy difference constraint) = 0.0027 to 0.27 eV, system-dependent
    User-chosen constraint defining the tube I_ε. For each S0/S1 system the paper reports the smallest ε that converged (ethylene 0.27 eV, azobenzene 0.20 eV, uracil 6S5 0.07 eV, oop-O 0.14 eV). SI Table 2 shows internal coordinates are nearly constant across ε for uracil, so the results are not tuned to the reference MECIs.
assumptions (5)
  • domain assumption The crossing seam I is a smooth, everywhere-differentiable Riemann manifold of dimension N-2.
    Stated in the introduction and used to justify the tube picture; standard for same-symmetry conical intersections, but not verified for the molecules studied.
  • domain assumption Near the intersection the degeneracy is lifted linearly in exactly two directions (double-cone topology), making I_ε an ellipse in the branching plane and a tube along the seam.
    Used to argue the ε-minimum approximates the MECI. The paper acknowledges linear intersections (symmetry or method artifacts) are a separate case.
  • ad hoc to paper For sufficiently small ε the minimizer of the upper-state energy on I_ε converges to the minimum energy conical intersection on I.
    Asserted in the paragraph after eq. 5 without proof; the only numerical demonstration is the S1/S2 uracil comparison with the gradient projection method.
  • standard math The map R to (E_m(R) - E_n(R)) has nonzero gradient on I_ε, so I_ε is a regular level set and the orthogonal projector P_ε is well-defined.
    Invoked implicitly to define P_ε = 1 - g g^T as the tangent-space projector; standard level-set theorem.
  • domain assumption CCSD analytical gradients provide an accurate description of the potential energy surfaces away from the degeneracy.
    Required so that g_nm and optimized geometries are meaningful; the ε-gap is precisely what keeps the optimization away from regions where CC fails.

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Pith. "Pith review of Determining minimum energy conical intersections by enveloping the seam: exploring ground and excited state intersections in coupled cluster theory." pith.science (2026). https://pith.science/paper/RB3BZCLW

@misc{pith2026241108207,
  author       = {Pith},
  title        = {Pith review of: Determining minimum energy conical intersections by enveloping the seam: exploring ground and excited state intersections in coupled cluster theory},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/RB3BZCLW}},
  note         = {Machine review of arXiv:2411.08207}
}
read the original abstract

Minimum energy conical intersections can be used to rationalize photochemical processes. In this Letter, we examine an algorithm to locate these structures that does not require the evaluation of nonadiabatic coupling vectors, showing that it minimizes the energy on hypersurfaces that envelop the intersection seam. By constraining the states to be separated by a small non-zero energy difference, the algorithm ensures that numerical artifacts and convergence problems of coupled cluster theory at conical intersections are not encountered during the optimization. In this way, we demonstrate for various systems that minimum energy conical intersections with the ground state are well described by the coupled cluster singles and doubles model, suggesting that coupled cluster theory may in some cases provide a good description of relaxation to the ground state in nonadiabatic dynamics simulations.

Figures

Figures reproduced from arXiv: 2411.08207 by the authors.

Figure 1
Figure 1. The intersecting energy surfaces describe a double cone in the g-h plane (top left). The energy difference is ε along an ellipse identified by Iε. The crossing seam I is orthogonal to the plane. Moving along the seam, Iε describes a tube (center). In both the gradient projection method 10 (top right) and the tube algorithm (bottom right), I or Iε are first reached from the starting guess. Then, the energy of the upp… view at source ↗
Figure 2
Figure 2. Illustration of a step-wise optimization of a S1/S2 ε-MECI for uracil, using CCSD (ε=0.14, 0.027 eV) and SCCSD (ε=0.014, 0.0027 eV), and comparison with the MECI determined using the gradient projection method (with SCCSD). The basis set is cc-pVDZ. Bond lengths are expressed in Å and angles in degrees (◦ ). The optimized geometries from the gradient projection method, the tube algorithm with ε = 0.027 eV and ε = 0.… view at source ↗
Figure 3
Figure 3. The S0/S1 pyramidalized MECI for ethylene. Internal coordinates for the CCSD ε-MECI are shown for ε= 0.27 eV, basis set aug-cc-pVDZ. Reference values from Ref. 38 determined with 2SA￾CASSCF(4/7)/aug-cc-pVDZ are reported in parenthesis. Bond lengths are expressed in Å and angles in degrees (◦ ). For azobenzene, we focus on an S0/S1 MECI (CI-rot) involved in the photoinduced cis￾trans isomerization reaction. 39 In [P… view at source ↗
Figures from the paper (4 more)
Figure 4
Figure 4. Figure 4: S0/S1 MECI for azobenzene with 5SA-CASSCF(6/6)/6-31G from Ref. 39 (left) and ε-MECI with CCSD/6-31G (right). ε= 0.20 eV. Further comparison of internal coordinates is provided in the Supporting Information. Finally, we consider two S0/S1 MECIs for uracil. The first one…
Figure 5
Figure 5. Figure 5: S0/S1 MECIs for uracil. The 6S5 structures were determined at the SF-TDDFT/6-31+G(d,p) level in Ref. 40 (top left), CASSCF (10/8)/6-31G* level in Ref. 41 (top center) and CCSD/cc-pVDZ ε=0.07 eV (top right). The oop-O structures were determined at the CASSCF(10/8)/6-31G…
Figure 1
Figure 1. Figure 1: Excitation energies of S1 and S2 over the number of iterations for an optimization using the gradient projection method (top) and a stepwise optimization using the tube algorithm (bottom). The grey line indicates the first convergence of the stepwise tube algorithm wit…
Figure 2
Figure 2. Figure 2: Root mean square displacement (rms) of the total gradient G12 and of the projection of g22 along the tube over the number of iterations for an optimization using the gradient projection method (top) and a stepwise optimization using the tube algorithm (bottom). The gre…

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Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

  1. Generalized coupled cluster theory for ground and excited state intersections

    physics.chem-ph 2024-11 conditional novelty 8.0 of 10

    A modified coupled cluster parametrization removes the bifurcations and geometric phase failures that blocked ground-state conical intersections.

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Works this paper leans on

44 extracted references · 38 canonical work pages · cited by 1 Pith paper

  1. [1]

    Yarkony, D. R. On the characterization of regions of avoided surface crossings using an analytic gradient based method. J. Chem. Phys. 1990, 92, 2457--2463

    work page 1990

  2. [2]

    Yarkony, D. R. Diabolical conical intersections. Rev. Mod. Phys. 1996, 68, 985

    work page 1996

  3. [3]

    J.; Xantheas, S

    Atchity, G. J.; Xantheas, S. S.; Ruedenberg, K. Potential energy surfaces near intersections. J. Chem. Phys. 1991, 95, 1862--1876

    work page 1991

  4. [4]

    Bernardi, F.; De, S.; Olivucci, M.; Robb, M. A. The mechanism of ground-state-forbidden photochemical pericyclic reactions: evidence for real conical intersections. J. Am. Chem. Soc. 1990, 112, 1737--1744

    work page 1990

  5. [5]

    von Neumann, J.; Wigner, E. P. \"U ber das Verhalten von Eigenwerten bei adiabatischen Prozessen. The Collected Works of Eugene Paul Wigner: Part A: The Scientific Papers 1993, 294--297

    work page 1993

  6. [6]

    Electronic structure methods for the description of nonadiabatic effects and conical intersections

    Matsika, S. Electronic structure methods for the description of nonadiabatic effects and conical intersections. Chem. Rev. 2021, 121, 9407--9449

    2021

  7. [7]

    Zhu, X.; Yarkony, D. R. Non-adiabaticity: the importance of conical intersections. Mol. Phys. 2016, 114, 1983--2013

    work page 2016

  8. [8]

    R.; Yarkony, D

    Manaa, M. R.; Yarkony, D. R. On the intersection of two potential energy surfaces of the same symmetry. Systematic characterization using a Lagrange multiplier constrained procedure. J. Chem. Phys. 1993, 99, 5251--5256

    work page 1993

Show all 44 references
  1. [9]

    Yarkony, D. R. Marching along ridges. Efficient location of energy-minimized conical intersections of two states using extrapolatable functions. J. Phys. Chem. A 2004, 108, 3200--3205

    2004

  2. [10]

    J.; Robb, M

    Bearpark, M. J.; Robb, M. A.; Bernhard Schlegel , H. A direct method for the location of the lowest energy point on a potential surface crossing. Chem. Phys. Letters 1994, 223, 269--274

    1994

  3. [11]

    J.; Robb, M

    Sicilia, F.; Blancafort, L.; Bearpark, M. J.; Robb, M. A. New algorithms for optimizing and linking conical intersection points. J. Chem. Theory Comput. 2008, 4, 257--266

    2008

  4. [12]

    G.; Coe, J

    Levine, B. G.; Coe, J. D.; Mart \' nez, T. J. Optimizing conical intersections without derivative coupling vectors: Application to multistate multireference second-order perturbation theory (MS-CASPT2). J. Phys. Chem. B 2008, 112, 405--413

    2008

  5. [13]

    Updated branching plane for finding conical intersections without coupling derivative vectors

    Maeda, S.; Ohno, K.; Morokuma, K. Updated branching plane for finding conical intersections without coupling derivative vectors. J. Chem. Theory Comput. 2010, 6, 1538--1545

    2010

  6. [14]

    Roos, B. O. The complete active space SCF method in a fock-matrix-based super-CI formulation. Int. J. Quantum Chem. 1980, 18, 175--189

    1980

  7. [15]

    Andersson, K.; Malmqvist, P.- .; Roos, B. O. Second-order perturbation theory with a complete active space self-consistent field reference function. J. Chem. Phys. 1992, 96, 1218--1226

    1992

  8. [16]

    Teh, H.-H.; Subotnik, J. E. The simplest possible approach for simulating S 0--S 1 conical intersections with DFT/TDDFT: Adding one doubly excited configuration. J. Phys. Chem. Lett. 2019, 10, 3426--3432

    2019

  9. [17]

    L.; Marenich, A

    Li, S. L.; Marenich, A. V.; Xu, X.; Truhlar, D. G. Configuration interaction-corrected Tamm--Dancoff approximation: A time-dependent density functional method with the correct dimensionality of conical intersections. J. Phys. Chem. Lett. 2014, 5, 322--328

    2014

  10. [18]

    A.; Truhlar, D

    Shu, Y.; Parker, K. A.; Truhlar, D. G. Dual-functional Tamm--Dancoff approximation: a convenient density functional method that correctly describes S1/S0 conical intersections. J. Phys. Chem. Lett. 2017, 8, 2107--2112

    2017

  11. [19]

    B.; Hermes, M

    Calio, P. B.; Hermes, M. R.; Bao, J. J.; Galv \'a n, I. F.; Lindh, R.; Truhlar, D. G.; Gagliardi, L. Minimum-Energy Conical Intersections by Compressed Multistate Pair-Density Functional Theory. J. Phys. Chem. A 2024, 128, 1698--1706

    2024

  12. [20]

    Structure optimizations for excited states with correlated second-order methods: CC2 and ADC (2)

    H \"a ttig, C. Structure optimizations for excited states with correlated second-order methods: CC2 and ADC (2). Adv. Quantum Chem. 2005, 50, 37--60

    2005

  13. [21]

    Can coupled-cluster theory treat conical intersections? J

    K \"o hn, A.; Tajti, A. Can coupled-cluster theory treat conical intersections? J. Chem. Phys. 2007, 127

    2007

  14. [22]

    G.; Ko, C.; Quenneville, J.; Mart \'I nez, T

    Levine, B. G.; Ko, C.; Quenneville, J.; Mart \'I nez, T. J. Conical intersections and double excitations in time-dependent density functional theory. Mol. Phys. 2006, 104, 1039--1051

    2006

  15. [23]

    F.; Koch, H

    Kj nstad, E. F.; Koch, H. Resolving the notorious case of conical intersections for coupled cluster dynamics. J. Phys. Chem. Lett. 2017, 8, 4801--4807

    2017

  16. [24]

    F.; Koch, H

    Kj nstad, E. F.; Koch, H. An orbital invariant similarity constrained coupled cluster model. J. Chem. Theory Comput. 2019, 15, 5386--5397

    2019

  17. [25]

    F.; Fajen, O

    Kjønstad, E. F.; Fajen, O. J.; Paul, A. C.; Angelico, S.; Mayer, D.; Gühr, M.; Wolf, T. J. A.; Martínez, T. J.; Koch, H. Unexpected hydrogen dissociation in thymine: predictions from a novel coupled cluster theory. 2024; https://arxiv.org/abs/2403.01045

    2024 arXiv

  18. [26]

    F.; Angelico, S.; Koch, H

    Kj nstad, E. F.; Angelico, S.; Koch, H. Coupled cluster theory for nonadiabatic dynamics: nuclear gradients and nonadiabatic couplings in similarity constrained coupled cluster theory. J. Chem. Theory Comput. 2024, 20, 7080--7092

    2024

  19. [27]

    F.; Angelico, S.; Koch, H

    Rossi, F.; Kjønstad, E. F.; Angelico, S.; Koch, H. Generalized coupled cluster theory for ground and excited state intersections. 2024; https://arxiv.org/abs/2411.08751

    2024 arXiv

  20. [28]

    Exploring approximate geometries of minimum energy conical intersections by TDDFT calculations

    Harabuchi, Y.; Hatanaka, M.; Maeda, S. Exploring approximate geometries of minimum energy conical intersections by TDDFT calculations. Chem. Phys. Letters 2019, 737, 100007

    2019

  21. [29]

    Analysis II; Birkhäuser Cham, 2008

    Amann, H.; Escher, J. Analysis II; Birkhäuser Cham, 2008

    2008

  22. [30]

    Longuet-Higgins, H. C. The intersection of potential energy surfaces in polyatomic molecules. Proc. Roy. Soc. 1975, A344, 147--156

    1975

  23. [31]

    F.; Koch, H

    Kjønstad, E. F.; Koch, H. Understanding failures in electronic structure methods arising from the geometric phase effect. 2024; https://arxiv.org/abs/2411.08209

    2024 arXiv

  24. [32]

    Koch, H.; J rgensen, P.; others Coupled cluster response functions. J. Chem. Phys. 1990, 93, 3333

    1990

  25. [33]

    F.; Bartlett, R

    Stanton, J. F.; Bartlett, R. J. The equation of motion coupled-cluster method. A systematic biorthogonal approach to molecular excitation energies, transition probabilities, and excited state properties. J. Chem. Phys. 1993, 98, 7029--7039

    1993

  26. [34]

    D.; Kj nstad, E

    Folkestad, S. D.; Kj nstad, E. F.; Myhre, R. H.; Andersen, J. H.; Balbi, A.; Coriani, S.; Giovannini, T.; Goletto, L.; Haugland, T. S.; Hutcheson, A. et al. eT 1.0: An open source electronic structure program with emphasis on coupled cluster and multilevel methods. J. Chem. Ph...

    2020

  27. [35]

    K.; Koch, H.; Coriani, S.; Kj nstad, E

    Schnack-Petersen, A. K.; Koch, H.; Coriani, S.; Kj nstad, E. F. Efficient implementation of molecular CCSD gradients with Cholesky-decomposed electron repulsion integrals. J. Chem. Phys. 2022, 156

    2022

  28. [36]

    The efficient optimization of molecular geometries using redundant internal coordinates

    Bakken, V.; Helgaker, T. The efficient optimization of molecular geometries using redundant internal coordinates. J. Chem. Phys. 2002, 117, 9160--9174

    2002

  29. [37]

    Determining minimum energy conical intersections by enveloping the seam: exploring ground and excited state intersections in coupled cluster theory

    Angelico, S.; Kj nstad, E. F.; Koch, H. Data for: "Determining minimum energy conical intersections by enveloping the seam: exploring ground and excited state intersections in coupled cluster theory". 10.5281/zenodo.14076462 2024,

    doi

  30. [38]

    Ben-Nun, M.; Mart ´ nez, T. J. Photodynamics of ethylene: ab initio studies of conical intersections. Chem. Phys. 2000, 259, 237--248

    2000

  31. [39]

    Probing the → * photoisomerization mechanism of cis-azobenzene by multi-state ab initio on-the-fly trajectory dynamics simulation

    Yu, L.; Xu, C.; Zhu, C. Probing the → * photoisomerization mechanism of cis-azobenzene by multi-state ab initio on-the-fly trajectory dynamics simulation. Phys. Chem. Chem. Phys. 2015, 17, 17646--17660

    2015

  32. [40]

    Zhang, X.; Herbert, J. M. Excited-State Deactivation Pathways in Uracil versus Hydrated Uracil: Solvatochromatic Shift in the 1 n * State is the Key. J. Phys. Chem. B 2014, 118, 7806--7817

    2014

  33. [41]

    J.; Szymczak, J

    Nachtigallov \'a , D.; Aquino, A. J.; Szymczak, J. J.; Barbatti, M.; Hobza, P.; Lischka, H. Nonadiabatic dynamics of uracil: Population split among different decay mechanisms. J. Phys. Chem. A 2011, 115, 5247--5255

    2011

  34. [42]

    Unified model for the ultrafast decay of pyrimidine nucleobases

    Merchan, M.; Gonzalez-Luque, R.; Climent, T.; Serrano-Andres, L.; Rodr \' guez, E.; Reguero, M.; Pelaez, D. Unified model for the ultrafast decay of pyrimidine nucleobases. J. Phys. Chem. B 2006, 110, 26471--26476

    2006

  35. [43]

    Photoinduced nonadiabatic dynamics of pyrimidine nucleobases: on-the-fly surface-hopping study with semiempirical methods

    Lan, Z.; Fabiano, E.; Thiel, W. Photoinduced nonadiabatic dynamics of pyrimidine nucleobases: on-the-fly surface-hopping study with semiempirical methods. J. Phys. Chem. B 2009, 113, 3548--3555

    2009

  36. [44]

    @NLkr Xj@r1N Ii/ c+ vW_! ?4 Kt9S A 5J LqTaKҌb u JOn ji+:+ LY ¾ # ( κC

    Matsika, S. Radiationless Decay of Excited States of Uracil through Conical Intersections. J. Phys. Chem. A 2004, 108, 7584--7590 mcitethebibliography main.tex0000664000000000000000000006530514715355713011250 0ustar rootroot [ journal=jpclcd, manuscript=letter, review ] achems...

    2004

Pith tools

Reviewed August 12, 2026 · model on record in the stance chip above.