Force Field Calculation Parameters in Chemistry
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Questions and Answers

What is a limitation of the MM3 force field with regard to vibrational spectra?

  • Rotational barriers are high
  • Accurate prediction for highly saturated hydrocarbons
  • Vibrational spectra are not accurately calculated (correct)
  • Partial double bonds in saturated molecules
  • Which of the following is affected by hyperconjugation according to the text?

  • Vibrational spectra of saturated hydrocarbons
  • Rotational barriers for alkenes
  • Improper torsion-torsion angles
  • Bond length changes in conjugated molecules (correct)
  • What dependency does hyperconjugation have on bond characteristics in molecules?

  • Inductive effect on molecular weight
  • Bond length changes due to higher H+ character (correct)
  • Higher stability in saturated hydrocarbons
  • Lowering the rotational barriers
  • In CHARMM, what type of chemistry is focused on by Harvard Macromolecular Mechanics?

    <p>Macromolecular mechanics</p> Signup and view all the answers

    What is a limitation of the MM4 force field in relation to saturated hydrocarbons?

    <p>High rotational barriers</p> Signup and view all the answers

    What type of force field parameter is used for electrostatic calculations?

    <p>Atom-centered monopole</p> Signup and view all the answers

    Which type of experiments are used for parametrization in proteins according to the text?

    <p>Microwave and X-ray</p> Signup and view all the answers

    What module in AMBER is used for minimization, molecular dynamics, and NMR refinements?

    <p>SANDER</p> Signup and view all the answers

    Which AMBER force field is generally recommended for proteins?

    <p>ff14SB</p> Signup and view all the answers

    What does the Replica exchange calculations in force field parameterization allow?

    <p>Simultaneous sampling at a variety of conditions</p> Signup and view all the answers

    In which type of calculations are provisions made for handling NOESY intensities and proton chemical shifts?

    <p>QM calculations</p> Signup and view all the answers

    What is the force field that accounts for all atoms in the periodic table?

    <p>UFF</p> Signup and view all the answers

    What type of potential is used to describe bond stretching in the UFF force field?

    <p>Morse potential</p> Signup and view all the answers

    What is the term used to describe the electrostatic interaction between charged atoms in the UFF force field?

    <p>Charge-Charge interaction</p> Signup and view all the answers

    How many atom types are defined in the UFF force field?

    <p>126</p> Signup and view all the answers

    What type of torsion term is used in the UFF force field?

    <p>Cosine torsion term</p> Signup and view all the answers

    What is the primary focus of the CHARMM22 force field reoptimization mentioned in the text?

    <p>Achieving equilibrium between A and B forms of DNA</p> Signup and view all the answers

    What aspect of the force field was specifically optimized for the TIP3P water model?

    <p>Scaling factors and offsets of interaction energies</p> Signup and view all the answers

    In what solvent was the stabilization of the B form of DNA observed during the simulation?

    <p>Aqueous solution</p> Signup and view all the answers

    What are the major simulations conducted for further validation of the reoptimized force field?

    <p>Structural, dynamic, and hydration parameters</p> Signup and view all the answers

    Which force field is specifically designed for all-atom simulations of proteins?

    <p>CHARMM36</p> Signup and view all the answers

    What was noted as a limitation in the CHARMM22 force field reoptimization according to the text?

    <p>Equilibrium between helical and extended conformations</p> Signup and view all the answers

    What improvement was made to the CMAP potential in the experiment described?

    <p>Refining with solution NMR data</p> Signup and view all the answers

    Which part of the backbone CMAP potential was corrected in the study?

    <p>α-helix and extended regions</p> Signup and view all the answers

    What aspect of the CHARMM22 Gly and Pro CMAPs was corrected?

    <p>Correcting α-helical bias</p> Signup and view all the answers

    What was the main focus of the experiments conducted with Ala3, Ala5, Ala7, Val3, and Gly3?

    <p>Equilibrium folding of β-hairpins</p> Signup and view all the answers

    Which technique was used to validate the experiments?

    <p>Comparison with backbone scalar couplings</p> Signup and view all the answers

    In what type of proteins did the MacKerell Group focus their study on, according to the text?

    <p>Unfolded proteins</p> Signup and view all the answers

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