Automated exploration of stable isomers of H+(H2O)n (n = 5–7) via ab initio calculations: An application of the anharmonic downward distortion following algorithm

The explicit polarization (X-Pol) method is a fragment-based quantum mechanical model, in which a macromolecular system in solution is partitioned into monomer fragments. The present study extends the original X-Pol method, where all fragments are treated using the same electronic structure theory, to a multilevel representations, called multilevel X-Pol, in which different electronic structure methods are used to describe different fragments. The multilevel X-Pol method has been implemented into Gaussian 09. A key ingredient that is used to couple interfragment electrostatic interactions at different levels of theory is the use of the response density for post-self-consistent-field energy (The response density is also called the generalized density). The method is useful for treating fragments in a small region of the system such as the solute molecules or the substrate and amino acids in the active site of an enzyme with a high-level theory, and the fragments in the rest of the system by a lower-level and computationally more efficient method. The method is illustrated here by applications to hydrogen bonding complexes in which one fragment is treated with the hybrid M06 density functional, Møller-Plesset perturbation theory, or coupled cluster theory, and the other fragments are treated by Hartree-Fock theory or the B3LYP or M06 hybrid density functionals.

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“…The optimized structure for the complex is very similar to that optimized using B3LYP/6-311+G(dp) from ref 87.…”

Section: Resultsmentioning

confidence: 61%

Multilevel X-Pol: A Fragment-Based Method with Mixed Quantum Mechanical Representations of Different Fragments

et al. 2012

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“…There can be many isomers and many local minima even for medium-sized PW clusters. Since structural properties of PW clusters are relevant to the understanding of thermodynamic properties and proton transfer mechanisms in aqueous solutions and biological systems, PW clusters have been extensively studied experimentally [1][2][3][4][5][6][7][8][9][10] as well as theoretically [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Since the number of possible structural isomers increases rapidly with the cluster size, it is difficult to present all of them even for medium-sized PW clusters.…”

Section: Introductionmentioning

confidence: 99%

A comprehensive search of topologically distinct local minimum structures of protonated water octamer and the classification of O H topological types

Akase¹,

Teramae²,

Aida³

2015

Chemical Physics Letters

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a b s t r a c tThe rooted digraph is used to topologically distinguish the isomers of protonated water (PW) cluster. We generated many PW octamer geometries and obtained 134 topologically distinct geometries of the PW octamers at the theoretical level of MP2/aug-cc-pVDZ. The temperature-dependent population ratios of those isomers were calculated. Dominant structures of PW octamers vary according to the temperature.The O H bonds of PW cluster were classified into 10 topological types according to the local hydrogenbonding network. The vibrational frequency of the same topological type of the O H bond, which is transferable in different isomers, can be used as a vibrational spectral signature.

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“…In 2002, we reached an algorithm, overcoming difficulties of the GRRM issue by noting potential distortions from harmonic potentials. Since then, a number of applications of the algorithm to GRRM problems have been made with many collaborators 9–60. Fundamental parts of our methods for GRRM were reported in some representative publications,9,12,19 and typical achievements were described in recent reviews 43,46,52…”

Section: Introductionmentioning

confidence: 99%

Study of Potential Energy Surfaces towards Global Reaction Route Mapping

Ohno

2016

The Chemical Record

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The potential energy surface (PES) is just a theoretical construct based on the Born-Oppenheimer approximation, but it underlies various phenomena, including molecular vibrations, collisional ionizations, and chemical reactions. This account describes how a new idea for global reaction route mapping (GRRM), which had seemed to be impossible for chemical systems with more than three atoms, was born and has been developed during the course of the study of the PES. GRRM has pioneered new fields of chemistry. Furthermore, techniques for GRRM are still developing, and GRRM is further extending its application to various areas of chemistry and chemical physics.

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Automated exploration of stable isomers of H⁺(H₂O)_n (n = 5–7) via ab initio calculations: An application of the anharmonic downward distortion following algorithm

Cited by 48 publications

References 91 publications

Multilevel X-Pol: A Fragment-Based Method with Mixed Quantum Mechanical Representations of Different Fragments

Multilevel X-Pol: A Fragment-Based Method with Mixed Quantum Mechanical Representations of Different Fragments

A comprehensive search of topologically distinct local minimum structures of protonated water octamer and the classification of O H topological types

Study of Potential Energy Surfaces towards Global Reaction Route Mapping

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