Author Archives: alan

Predicting NMR shifts for organoiodine compounds in Spartan

Shift prediction for RI (and ArI and I-anything) molecules is impossible using the 6-31G*basis set because these basis functions have not been defined for iodine. Use 6-311G*.

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‘Out of Memory’ Errors in Spartan

The computers in C203 are equipped with i7 8-core processors and 8G of total RAM. This occasionally leads to “out of memory” errors. These errors are particularly common during Spartan DFT IR calculations (a typical output error message reads, “Error … finish reading ‘Out of Memory’ Errors in Spartan

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Spartan tip – Natural Bond Orbitals

Parts of Weinhold’s Natural Population Analysis (NAO, NBO, but not NHO, NRT, perturbation calculations, etc.) have been part of Spartan from the very beginning, but the instructions for accessing this analysis keeps changing. Here is my understanding of what parts … finish reading Spartan tip – Natural Bond Orbitals

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Predicting bioactivity of toxic chemicals

Here’s the set up: I draw three chemical structures on the board, all of them unfamiliar. Then I ask you some questions: Which one has the strongest odor? Which one raises your body temperature the most? Which one is most … finish reading Predicting bioactivity of toxic chemicals

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Spartan tip – Symmetry errors

Spartan automatically examines models for symmetry. When it finds symmetry elements, it applies these in subsequent calculations. For example, if you build ‘flat’ NH3 (possible point groups: Cs, C3v, D3h, etc.) and calculate its equilibrium geometry, you will end up … finish reading Spartan tip – Symmetry errors

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Can a picture tell you whether a molecule is polar?

This question is asked in a particularly interesting way by G.E. Höst et al in the December issue of J. Chem. Ed. (“Students’ Use of Three Different Visual Representations to Interpret Whether Molecules are Polar or Nonpolar”, DOI: 10.1021/ed2001895). They … finish reading Can a picture tell you whether a molecule is polar?

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Adjust JPEG resolution in Spartan’08 (Windows)

This info has been knocking around my email inbox for a long time (rec’d from Wavefunction help on 9/15/2009), but while Spartan has moved on to Spartan’10 (’12 or ’13 just around the corner), maybe the advice is still useful.

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Sabbatical Winds Down … iSpartan Winds Up

My 2011-12 sabbatical is entering its final weeks and I am already receiving emails about college business that supposedly only I can deal with. Sigh. So whatever happened to that long list of possible sabbatical projects I outlined last… Continue reading

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Converting Total Energy to Enthalpy, 298K, 1 atm

The total energy is obtained from a model in which the nuclei are frozen in place. Therefore, the total energy fails to include the kinetic energy of the nuclei and cannot be compared directly to the standard enthalpy, H,… Continue reading

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Pseudopotentials in Spartan'10

The Setup: Calculations dialog in Spartan'10 does not contain a checkbox for pseudopotentials, but they are there (just hidden).I tried the following experiments with M(CO)4 and B3LYP. Each produced a slightly different result.Setup: M = Ni, 6-31G* (menu). Result: All-electron… Continue reading

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