scholarly journals Calculating energy derivatives for quantum chemistry on a quantum computer

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Thomas E. O’Brien ◽  
Bruno Senjean ◽  
Ramiro Sagastizabal ◽  
Xavier Bonet-Monroig ◽  
Alicja Dutkiewicz ◽  
...  
Keyword(s):  
Bond Length ◽  
Quantum Computer ◽  
Survey Methods ◽  
Geometry Optimization ◽  
Equilibrium Bond Length ◽  
Molecular Systems ◽  
Energy Derivatives ◽  
Quantum Processor ◽  
Dynamics Simulations ◽  
Derivatives Of

AbstractModeling chemical reactions and complicated molecular systems has been proposed as the “killer application” of a future quantum computer. Accurate calculations of derivatives of molecular eigenenergies are essential toward this end, allowing for geometry optimization, transition state searches, predictions of the response to an applied electric or magnetic field, and molecular dynamics simulations. In this work, we survey methods to calculate energy derivatives, and present two new methods: one based on quantum phase estimation, the other on a low-order response approximation. We calculate asymptotic error bounds and approximate computational scalings for the methods presented. Implementing these methods, we perform geometry optimization on an experimental quantum processor, estimating the equilibrium bond length of the dihydrogen molecule to within $$0.014$$0.014 Å of the full configuration interaction value. Within the same experiment, we estimate the polarizability of the H$${}_{2}$$2 molecule, finding agreement at the equilibrium bond length to within $$0.06$$0.06 a.u. ($$2 \%$$2% relative error).

scholarly journals Plutonium complexes in water: new approach to ab initio modeling

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mikhail V. Ryzhkov ◽  
Andrei N. Enyashin ◽  
Bernard Delley
Keyword(s):  
Quantitative Estimation ◽  
Water Solution ◽  
Geometry Optimization ◽  
Model Potential ◽  
Water Dissociation ◽  
New Approach ◽  
Molecular Systems ◽  
Screening Model ◽  
Solvent Environment ◽  
Structure Calculations

Abstract Geometry optimization and the electronic structure calculations of Pu Z+ complexes (Z = 3–6) in water solution have been performed, within the framework of the DMol3 and Relativistic Discrete-Variational (RDV) methods. For the simulation of Pu Z+ molecular environment in aqueous solution we used 22 and 32 water molecules randomly distributed around cation. To model the effect of bulk solvent environment we used COSMO (Conductor-like Screening Model) potential for water (ε = 78.54). The obtained results showed that this approach allows the modeling of water dissociation and the formation of hydrolysis products. Our previously suggested scheme for the calculation of interaction energies between selected fragments of multi-molecular systems provides the quantitative estimation of the interaction strengths between plutonium in various oxidation states and each ligand in the first and second coordination shells in water solution.

scholarly journals Molecular-Dynamics Simulations of C- and N-Terminal Peptide Derivatives of GCN4-p1 in Aqueous Solution

2005 ◽  
Vol 2 (8) ◽  
pp. 1086-1104 ◽  
Author(s):  
John H. Missimer ◽  
Michel O. Steinmetz ◽  
Wolfgang Jahnke ◽  
Fritz K. Winkler ◽  
Wilfred F. van Gunsteren ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Aqueous Solution ◽  
Molecular Dynamics Simulations ◽  
Peptide Derivatives ◽  
C And N ◽  
Dynamics Simulations ◽  
Derivatives Of

Syntheses, geometry optimization, and electronic structure of N-and C-substituted benzonaphthyridines

2006 ◽  
Vol 60 (1) ◽  
Author(s):  
M. Deska ◽  
W. Śliwa
Keyword(s):  
Electronic Structure ◽  
Ab Initio ◽  
13C Nmr ◽  
Effective Charge ◽  
Nmr Spectra ◽  
Geometry Optimization ◽  
13C Nmr Spectra ◽  
Derivatives Of ◽  
Hydroxyethyl Group

AbstractSynthesis of N-and C-substituted derivatives of benzo[h][1,6]naphthyridine, bearing 2-hydroxyethyl group has been made by quaternization reaction and by condensation of corresponding methylbenzonaphthyridines with formaldehyde. For six derivatives of isomeric benzo[c][1,5]-, benzo[h][1,6]-, and benzo[f][1,7]naphthyridines the 13C NMR spectra are discussed.For ten compounds the geometry was optimized with the AM1 and, in one case also with the ab initio 6–31G method; their effective charge values have also been calculated.

scholarly journals NMR Determination of Amide N−H Equilibrium Bond Length from Concerted Dipolar Coupling Measurements

2008 ◽  
Vol 130 (49) ◽  
pp. 16518-16520 ◽  
Author(s):  
Lishan Yao ◽  
Beat Vögeli ◽  
Jinfa Ying ◽  
Ad Bax
Keyword(s):  
Bond Length ◽  
Dipolar Coupling ◽  
Equilibrium Bond Length

Pseudoacids. II. 2-Acylbenzoic Acid Derivatives

1998 ◽  
Vol 54 (3) ◽  
pp. 264-276 ◽  
Author(s):  
E. J. Valente ◽  
S. B. Martin ◽  
L. D. Sullivan
Keyword(s):  
Bond Length ◽  
Tertiary Amide ◽  
Derivatives Of

Structures of derivatives of cyclic o-acylbenzoic acids, including the chloride, endo- and exocyclic amides, esters and anhydrides, are examined. 3-Chloro-1(3H)-isobenzofuranone (1), orthorhombic, Pbca, a = 11.616 (5), b = 8.120 (3), c = 15.640 (9) Å; 3-methoxy-3-phenyl-1(3H)-isobenzofuranone (3), orthorhombic, P212121, a = 6.923 (2), b = 8.291 (4), c = 21.551 (8) Å; 3-hydroxy-3-phenyl-N-propyl-1(3H)-isoindolone (4), orthorhombic, P212121, a = 8.662 (4), b = 9.551 (7), c = 17.649 (14) Å; 3-(N-morpholino)-1(3H)-isobenzofuranone (5), triclinic, P1¯, a = 6.172 (4), b = 11.163 (7), c = 17.33 (2) Å, α = 105.91 (6), β = 99.85 (6), γ = 97.57 (5)°; 3-(2′-benzoylbenzoyloxy)-3-phenyl-1(3H)-isobenzofuranone (7), triclinic, P1¯, a = 9.694 (3), b = 10.505 (4), c = 11.163 (4) Å, α = 80.58 (3), β = 80.41 (3), γ = 76.49 (3)°; bis[1(3H)-isobenzofuranone-3-yl]ether (8), monoclinic, I2/a, a = 15.31 (2), b = 6.111 (12), c = 28.30 (5) Å, β = 101.61 (12)°. An open oxoacid tertiary amide is also described: N-morpholino 2′-benzoylbenzamide (6): monoclinic, P21/c, a = 6.844 (4), b = 15.696 (8), c = 14.154 (7) Å, β = 99.43 (4)°. Pseudoacid derivatives form planar isobenzofuran and isoindole rings, and the former aldehyde/ketone carbon–heteroatom endocyclic and exocyclic bond distances show bond length variations which correlate with the relative basicities of the attached groups. Structures of both endocyclic and exocyclic nitrogen pseudoamides are reported as well as examples of the normal–pseudoanhydride and the dipseudoanhydride.

Accurate ab initio Calculations of Methane Dimer Interaction Energies and Molecular Dynamics Simulation of Fluid Methane

2009 ◽  
Vol 1177 ◽  
Author(s):  
Arvin Huang-Te Li ◽  
Sheng Der Chao
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Binding Energy ◽  
Ab Initio ◽  
Bond Length ◽  
Dynamics Simulation ◽  
Basis Set ◽  
Basis Sets ◽  
Equilibrium Bond Length ◽  
Basis Size

AbstractIntermolecular interaction potentials of the methane dimers have been calculated for 12 symmetric conformations using the Hartree-Fock (HF) self-consistent theory, the second-order M�ller-Plesset (MP2) perturbation theory, and the coupled-cluster with single and double and perturbative triple excitations (CCSD(T)) theory. The HF calculations yield unbound potentials largely due to the exchange-repulsion interaction. In MP2 and CCSD(T) calculations, the basis set effects on the repulsion exponent, the equilibrium bond length, the binding energy, and the asymptotic behavior of the calculated intermolecular potentials have been thoroughly studied. We have employed basis sets from the Slater-type orbitals fitted with Gaussian functions, Pople�s medium size basis sets to Dunning�s correlation consistent basis sets. With increasing basis size, the repulsion exponent and the equilibrium bond length converge at the 6-31G** basis set and the 6-311++G(2d, 2p) basis set, respectively, while a large basis set (aug-cc-pVTZ) is required to converge the binding energy at a chemical accuracy (˜0.01 kcal/mol). We used the BSSE corrected results that systematically converge to the destined potential curve with increasing basis size. The binding energy calculated and the equilibrium bond length using the CCSD(T) method are close to the results at the basis set limit. For molecular dynamics simulation, a 4-site potential model with sites located at the hydrogen atoms was used to fit the ab initio potential data. This model stems from a hydrogen-hydrogen repulsion mechanism to explain the stability of the dimer structure. MD simulations using the ab initio PES show good agreement on both the atom-wise radial distribution functions and the self-diffusion coefficients over a wide range of experimental conditions.

Extraction of Dunham Coefficients from Murrell-Sorbie Parameters

2008 ◽  
Vol 63 (1-2) ◽  
pp. 1-6 ◽  
Author(s):  
Teik-Cheng Lim
Keyword(s):  
Potential Energy ◽  
Bond Length ◽  
Potential Function ◽  
Series Expansion ◽  
Taylor Series ◽  
Energy Function ◽  
Taylor Series Expansion ◽  
Potential Energy Function ◽  
Reliable Data ◽  
Equilibrium Bond Length

A set of relationships between parameters of the Dunham and Murrell-Sorbie potential energy function is developed. By employing Taylor series expansion and comparison of terms arranged in increasing order of bond length, a set of Dunham coefficients is obtained as functions of Murrell- Sorbie parameters. The conversion functions reveal the importance of factorials in extracting Dunham coefficients from Murrell-Sorbie parameters. Plots of both functions, based on parameters of the latter, reveal good correlation near the equilibrium bond length for a group of diatomic molecules. Potential function relations, such as that shown in this paper, are useful when the preferred/reliable data is based on a potential function different from that adopted in available computational software.

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