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Stylianakis I, Zervos N, Lii JH, Pantazis DA, Kolocouris A. Conformational energies of reference organic molecules: benchmarking of common efficient computational methods against coupled cluster theory. J Comput Aided Mol Des 2023; 37:607-656. [PMID: 37597063 PMCID: PMC10618395 DOI: 10.1007/s10822-023-00513-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 06/03/2023] [Indexed: 08/21/2023]
Abstract
We selected 145 reference organic molecules that include model fragments used in computer-aided drug design. We calculated 158 conformational energies and barriers using force fields, with wide applicability in commercial and free softwares and extensive application on the calculation of conformational energies of organic molecules, e.g. the UFF and DREIDING force fields, the Allinger's force fields MM3-96, MM3-00, MM4-8, the MM2-91 clones MMX and MM+, the MMFF94 force field, MM4, ab initio Hartree-Fock (HF) theory with different basis sets, the standard density functional theory B3LYP, the second-order post-HF MP2 theory and the Domain-based Local Pair Natural Orbital Coupled Cluster DLPNO-CCSD(T) theory, with the latter used for accurate reference values. The data set of the organic molecules includes hydrocarbons, haloalkanes, conjugated compounds, and oxygen-, nitrogen-, phosphorus- and sulphur-containing compounds. We reviewed in detail the conformational aspects of these model organic molecules providing the current understanding of the steric and electronic factors that determine the stability of low energy conformers and the literature including previous experimental observations and calculated findings. While progress on the computer hardware allows the calculations of thousands of conformations for later use in drug design projects, this study is an update from previous classical studies that used, as reference values, experimental ones using a variety of methods and different environments. The lowest mean error against the DLPNO-CCSD(T) reference was calculated for MP2 (0.35 kcal mol-1), followed by B3LYP (0.69 kcal mol-1) and the HF theories (0.81-1.0 kcal mol-1). As regards the force fields, the lowest errors were observed for the Allinger's force fields MM3-00 (1.28 kcal mol-1), ΜΜ3-96 (1.40 kcal mol-1) and the Halgren's MMFF94 force field (1.30 kcal mol-1) and then for the MM2-91 clones MMX (1.77 kcal mol-1) and MM+ (2.01 kcal mol-1) and MM4 (2.05 kcal mol-1). The DREIDING (3.63 kcal mol-1) and UFF (3.77 kcal mol-1) force fields have the lowest performance. These model organic molecules we used are often present as fragments in drug-like molecules. The values calculated using DLPNO-CCSD(T) make up a valuable data set for further comparisons and for improved force field parameterization.
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Affiliation(s)
- Ioannis Stylianakis
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771, Athens, Greece
| | - Nikolaos Zervos
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771, Athens, Greece
| | - Jenn-Huei Lii
- Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Antonios Kolocouris
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771, Athens, Greece.
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, 15771, Athens, Greece.
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Tripathi P, Mitsari E, Romanini M, Serra P, Tamarit JL, Zuriaga M, Macovez R. Orientational relaxations in solid (1,1,2,2)tetrachloroethane. J Chem Phys 2016; 144:164505. [PMID: 27131555 DOI: 10.1063/1.4947477] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We employ dielectric spectroscopy and molecular dynamic simulations to investigate the dipolar dynamics in the orientationally disordered solid phase of (1,1,2,2)tetrachloroethane. Three distinct orientational dynamics are observed as separate dielectric loss features, all characterized by a simply activated temperature dependence. The slower process, associated to a glassy transition at 156 ± 1 K, corresponds to a cooperative motion by which each molecule rotates by 180° around the molecular symmetry axis through an intermediate state in which the symmetry axis is oriented roughly orthogonally to the initial and final states. Of the other two dipolar relaxations, the intermediate one is the Johari-Goldstein precursor relaxation of the cooperative dynamics, while the fastest process corresponds to an orientational fluctuation of single molecules into a higher-energy orientation. The Kirkwood correlation factor of the cooperative relaxation is of the order of one tenth, indicating that the molecular dipoles maintain on average a strong antiparallel alignment during their collective motion. These findings show that the combination of dielectric spectroscopy and molecular simulations allows studying in great detail the orientational dynamics in molecular solids.
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Affiliation(s)
- P Tripathi
- Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain
| | - E Mitsari
- Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain
| | - M Romanini
- Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain
| | - P Serra
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - J Ll Tamarit
- Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain
| | - M Zuriaga
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - R Macovez
- Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, ETSEIB, Diagonal 647, 08028 Barcelona, Spain
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Pérez SC, Zuriaga M, Serra P, Wolfenson A, Negrier P, Tamarit JL. Dynamic characterization of crystalline and glass phases of deuterated 1,1,2,2 tetrachloroethane. J Chem Phys 2015; 143:134502. [DOI: 10.1063/1.4931824] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Silvina C. Pérez
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - Mariano Zuriaga
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - Pablo Serra
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - Alberto Wolfenson
- Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - Philippe Negrier
- Université Bordeaux, LOMA, UMR 5798, F-33400 Talence, France and LOMA, UMR 5798, F-33400 Talence, France
| | - Josep Lluis Tamarit
- Grup de Caracterització de Materials, Departament de Física i Enginyeria Nuclear, ETSEIB, Diagonal 647, Universitat Politècnica de Catalunya, 08028 Barcelona, Catalonia, Spain
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Hammarström LG, Liljefors T, Gasteiger J. Electrostatic interactions in molecular mechanics (MM2) calculations via PEOE partial charges I. Haloalkanes. J Comput Chem 2004. [DOI: 10.1002/jcc.540090418] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Durig JR, Zheng C, Qtaitat MA, Deng S, Guirgis GA. Conformational stability from variable temperature infrared spectra of krypton solutions of 1,3-dichloropropane. J Mol Struct 2003. [DOI: 10.1016/s0022-2860(03)00454-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Johansen TH, Wold KH, Hagen K, Stølevik R. Chloromethyldichloromethylsilane and chloromethyldimethylchlorosilane: structure, conformational composition and torsional potential determined by gas-phase electron diffraction and ab initio molecular orbital calculations. J Mol Struct 1996. [DOI: 10.1016/s0022-2860(96)09330-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Gundertofte K, Liljefors T, Norrby PO, Pettersson I. A comparison of conformational energies calculated by several molecular mechanics methods. J Comput Chem 1996. [DOI: 10.1002/(sici)1096-987x(199603)17:4<429::aid-jcc5>3.0.co;2-w] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Johansen TH, Stølevik R. Symmetrically substituted silanes: (XH2C)2SiH2, (XH2C)2SiX2, (X2HC)2SiH2 and (X2HC)2SiX2 with X F, Cl or Br. Conformational energies, structures and torsional force constants obtained by molecular-mechanics calculations. J Mol Struct 1995. [DOI: 10.1016/0022-2860(95)08978-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Hagen K, Stølevik R. Structure and conformation of 1-Bromopropane: A gas-phase electron-diffraction investigation using microwave-spectroscopy data and results from ab initio calculations as constraints. Struct Chem 1995. [DOI: 10.1007/bf02286445] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Postmyr L. The molecular structures and conformational compositions of 1-bromo-3-chloropropane and 1,3-diiodopropane, as determined by gas-phase electron diffraction and molecular mechanics calculations. J Mol Struct 1994. [DOI: 10.1016/0022-2860(93)07918-m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Internal rotation in some symmetrically halogenated propanes, obtained by molecular mechanics calculations. J Mol Struct 1994. [DOI: 10.1016/0022-2860(93)07870-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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1,3-Dihalogenated (F, Cl, Br, I) propanes: torsional potentials, conformational structures and torsional force constants, as obtained by molecular mechanics calculations. J Mol Struct 1993. [DOI: 10.1016/0022-2860(93)80215-h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Postmyr L. Conformational structures and torsional potentials of some 1,2-dihalogenated-1,1,2,3,3,3-hexafluoropropanes, as obtained by molecular mechanics calculations. J Mol Struct 1993. [DOI: 10.1016/0022-2860(93)80216-i] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Stølevik R. Halogenated alkanes Part I. Empirical rules for calculating conformational energies. J Mol Struct 1993. [DOI: 10.1016/0022-2860(93)80254-s] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Xu S, Harmony MD. Microwave spectral study of 3-chloropropionitrile and 3-bromoproprionitrile. J Mol Struct 1992. [DOI: 10.1016/0022-2860(92)80151-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Gundertofte K, Palm J, Pettersson I, Stamvik A. A comparison of conformational energies calculated by molecular mechanics (MM2(85), Sybyl 5.1, Sybyl 5.21, and ChemX) and semiempirical (AM1 and PM3) methods. J Comput Chem 1991. [DOI: 10.1002/jcc.540120209] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Rotational potential energy functions in ethylchlorosilane,(chloromethyl)methylsilane, and (chloromethyl) chlorosilane: MM2, MNDO, and ab initio calculations. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0166-1280(90)85063-s] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Non-bonding potentials for the atom⋯atom interactions F⋯C, F⋯N, C⋯C, C⋯N and N⋯N as derived from conformational data using molecular mechanics calculations. J Mol Struct 1989. [DOI: 10.1016/0022-2860(89)85128-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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21
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Conformational analysis of 1,2-dihalo-tetramethylethanes and 1,2-dihalo-tetramethyldisilanes by molecular mechanics calculations. J Mol Struct 1989. [DOI: 10.1016/0022-2860(89)85156-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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22
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Conformational analysis of 4-chloro butanenitrile and 4-bromobutanenitrile using gas-phase electron diffraction and molecular mechanics calculations. J Mol Struct 1989. [DOI: 10.1016/0022-2860(89)85024-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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23
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Conformational structures and torsional potentials in 1,1,2,3-tetrahalogen (F, Cl, Br) propanes. J Mol Struct 1989. [DOI: 10.1016/0022-2860(89)85023-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Conformational energetics of 1,3-dichloropropane as predicted by several calculations methods. J Comput Chem 1988. [DOI: 10.1002/jcc.540090614] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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26
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Crowder G. Conformational analysis of 1,2-dibromo-2-methylpentane. J Mol Struct 1988. [DOI: 10.1016/0022-2860(88)85032-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stavnebrekk PJ, Stølevik R. Molecular mechanics calculations for conformational energies and torional force constants in fluoro propenes and butenes. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)85081-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Stavnebrekk PJ, Stølevik R. Molecular mechanics calculations of conformational structures, energies and torsional force constants in some bromopropenes and bromobutenes. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)87013-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stølevik R, Bakken P. Torsional potentials and conformational structures for 3-chloropropanal ClH2CCH2CHO and 3-chloropropanoyl chloride ClH2CCH2CClO and parameter values for the nonbonding interaction C(sp3) ⋯ O(carbonyl) as used in molecular-mechanics calculations. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)80050-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stavnebrekk PJ, Stølevik R. Potentials for the non-bonded atom ⋯atom interactions Cl⋯C(sp2) and C(sp3)⋯C(sp2) as derived from gas-phase data on chloropropenes and butenes using molecular mechanics calculations. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)85014-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bostrøm GO, Bakken P, Stølevik R. Torsional potentials and conformational structures in the halogen substituted molecules HOCCH2X, HOCCHX2, XOCCH2X, XOCCHX2, XH2CCOCH3, X2HCCOCH3, (XH2C)2CO, (X2HC)2CO, and (X3C)2CO (X = Cl, Br) as determined by molecular-mechanics calculations. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)80002-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Non-bonded potentials for the atom—atom interactions Cl⋯OC and H⋯OC as derived from gas-phase data using molecular-mechanics calculations. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)87026-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Thomassen H, Hagen K, Stølevik R, Hassler K. 1,1,2,2-tetrabromodisilane: gas-phase molecular structure and conformational composition as determined by electron diffraction. J Mol Struct 1986. [DOI: 10.1016/0022-2860(86)80387-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Stølevik R, Bakken P. Molecular-mechanics calculations for (XH2C)2O and (Xh2C)2S molecules with X = F, Cl and Br. J Mol Struct 1986. [DOI: 10.1016/0022-2860(86)85033-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Stølevik R, Bakken P. Molecular-mechanics calculations for H2C(CX3)2, X2C(CX3)2, H2Si(CX3)2 and X2Si(CX3)2 molecules with X=F, Cl and Br. J Mol Struct 1986. [DOI: 10.1016/0022-2860(86)85032-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Stølevik R, Bakken P. Conformational energies, rotational barrier heights and molecular structures in Si(CH2X)4 molecules (X = F, Cl, Br). J Mol Struct 1986. [DOI: 10.1016/0022-2860(86)85006-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Stølevik R, Bakken P. Conformational analysis of the halogenated (XF, Cl, Br) molecules (XH2C)2C(CH3)2 and (XH2C)2)Si(CH3)2 using molecular-mechanics calculations. J Mol Struct 1986. [DOI: 10.1016/0022-2860(86)85008-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Stølevik R, Bakken P. Conformational structures, energies, rotational barrier heights and torsional force constants in halogenated (X = F, Cl, Br) silanes with general formulas XH2CSiH2CH3 and XH2CXSiHCH3. J Mol Struct 1986. [DOI: 10.1016/0022-2860(86)80173-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Schei S, Hilderbrandt R. 1-Chloro-2-methylpropane: gas phase molecular structure and conformations as determined by a combined analysis of electron diffraction and microwave spectroscopic data, and calculated by molecular mechanics. J Mol Struct 1985. [DOI: 10.1016/0022-2860(85)85050-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Schei S, Stølevik R. Conformation and molecular structure of 1,2-dichloropropane and 1,2-dibromopropane as determined by gas-phase electron diffraction and molecular-mechanics calculation. J Mol Struct 1985. [DOI: 10.1016/0022-2860(85)85049-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stölevik R, Bakken P. Molecular mechanics calculations of conformational structures, energies, rotational barrier heights and torsional force constants in halogenated disilanes, hexachloroethane and trichloromethyl-trichlorosilane. ACTA ACUST UNITED AC 1985. [DOI: 10.1016/0166-1280(85)87025-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Stølevik R. Parameter values of non-bonded atom—atom interactions in the morse-potential formulation. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0166-1280(84)80025-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Stølevik R, Thingstad Ø. Molecular mechanics calculations of conformational structures, energies and torsional force constants in halogen-substituted propenes, 1,3-butadienes and biphenyls. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/0166-1280(84)85038-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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