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Published byValerie Clarke Modified over 8 years ago
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Plotting mathematical functions CSC 1521
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Scenario CSC 1522
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Domain We need to know the desired starting and ending values of the variable. Our variable is r the distance between the atoms, and we will start by looking at the function starting at r=0.2 and ending at r=1.0 (nanometers). Next we must decide on the intermediate values between 0.2 and 1.0. Let us go up by 0.001’s. CSC 1523
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Make a place for the parameters at the top, start the set of r values at 0.2 and enter a formula like =A6+0.001. Copy that down until you get to the desired ending value CSC 1524
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Enter the formula for the potential, something like =4*B$2*((B$3/A6)^12-(B$3/A6)^6). Note the use of absolute addressing (dollar signs) with the parameters. CSC 1525
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Make an XY Scatter Graph of the data and also find its minimum CSC 1526
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Scale the y axis to vary from -1 to 2. Scale the x axis to vary from 0 to 1. CSC 1527
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Create columns for the average consecutive r value =AVERAGE(A6:A7) and the Approximate derivative = (B7-B6)/(A7-A6) (Note it’s rise over run.) CSC 1528
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Here we are just testing an idea from calculus that the minimum occurs where the derivative changes sign (is zero) CSC 1529
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Change the ε parameter controls the depth of the “well” CSC 15210
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The σ parameter controls the r-value at which the minimum occurs CSC 15211
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References http://polymer.bu.edu/Wasser/robert/work/n ode8.html CSC 15212
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