ElemCo.jl Documentation

ElemCo.jl is a Julia package for computing electronic structure properties of molecules and materials. It provides a set of tools for performing quantum chemical calculations, including Hartree-Fock and post-HF methods.

Installation

You can install ElemCo.jl using the Julia package manager:

julia> using Pkg
julia> Pkg.add("ElemCo")

For a development version of ElemCo.jl, clone the repository and create an alias to set the project to the ElemCo.jl directory,

alias jlm='julia --project=<path_to_ElemCo.jl>'

Now the command jlm can be used to start the calculations,

jlm input.jl

Usage

Computing density-fitted Hartree-Fock and Coupled Cluster methods

To compute density-fitted Hartree-Fock (DF-HF) using ElemCo.jl, you can use the @dfhf macro. In order to run post-HF calculations, the integrals have to be transformed to the MO basis (using the @dfints macro), and the coupled cluster calculations can be performed using @cc macro. The @dfints macro is optional, @cc macro will automatically call @dfints if it has not been called before. Here's an example of how you can use these macros:

using ElemCo

# Print input to the output file
@print_input
# Define the molecule
geometry="bohr
     O      0.000000000    0.000000000   -0.130186067
     H1     0.000000000    1.489124508    1.033245507
     H2     0.000000000   -1.489124508    1.033245507"


basis = Dict("ao"=>"cc-pVDZ",
             "jkfit"=>"cc-pvtz-jkfit",
             "mp2fit"=>"cc-pvdz-rifit")

# Compute DF-HF 
@dfhf
# Calculate MO integrals (optional)
@dfints
# Run CCSD(T) calculation
@cc ccsd(t)

This code defines a water molecule, computes DF-HF using the cc-pVDZ basis set, calculates integrals using density fitting (mp2fit basis) and computes CCSD(T) energy.

Setting options

To set options (ElemCo.ECInfos.Options) for the DF-HF, CC, etc calculations, you can use the @opt macro. Here's an example of how you can use this macro:

# Set the maximum number of iterations to 10
@opt scf maxit=10

# Compute DF-HF using the new options
@dfhf

This code sets the maximum number of iterations for the SCF procedure to 10 using the @opt macro, and then computes DF-HF using the new options using the @dfhf macro.

Documentation

Equations for the methods implemented in ElemCo.jl.