4.10 Ground State Method Summary

To summarize the main features of Q-Chem’s ground state self-consistent field capabilities, the user needs to consider:

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  Input a molecular geometry ($molecule keyword)

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    Cartesian

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    Z-matrix

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    Read from prior calculations

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  Declare the job specification ($rem keyword)

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    JOBTYPE

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      Single point

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      Optimization

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      Frequency

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      See Table 4.1 for further options

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    BASIS

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      Refer to Chapter 8 (note: $basis keyword for user defined basis sets)

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      Effective core potentials (if desired); refer to Chapter 9

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    METHOD

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      Single method specification for exchange and correlation. Alternatively these can be specified separately.

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    EXCHANGE

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      Linear scaling algorithms for all methods

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      Arsenal of exchange density functionals

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      User definable functionals and hybrids

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    CORRELATION

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      DFT or wave function-based methods

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      Linear scaling (CPU and memory) incorporation of correlation with DFT

    • *

      Arsenal of correlation density functionals

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      User definable functionals and hybrids

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      See Chapter 6 for wave function-based correlation methods.

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  Exploit Q-Chem’s special features

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    CFMM, LinK large molecule options

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    SCF rate of convergence increased through improved guesses and alternative minimization algorithms

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    Explore novel methods if desired: CASE approximation, PAOs.