Ethanol Orbital Optimization¶

This tutorial focuses on optimizing orbital coefficients for Ethanol (\(C_2H_6O\)) using VMC. It is based on a test setup designed to verify QMCkl integration with TREXIO.

Input File Setup¶

Input File: vmc_ethanol_opt.inp

%module general
    title        'Ethanol vmc calculation jastrow and orbitals'
    mode         'vmc_one_mpi'
%endmodule

load trexio          ethanol.hdf5

load determinants    ethanol_rhf.det 
load jastrow         jastrow_optimized.jas
load jastrow_der     jastrow.der

%module optwf
    ioptwf        1 
    ioptci        0 
    ioptjas       0       # Jastrow fixed (previously optimized)
    ioptorb       1       # Optimize Orbitals
    method        'sr_n'
    ncore         0
    nextorb       250 
    isample_cmat  0       # Sampling controls
%endmodule

Description¶

Orbital optimization allows the nodal surface of the wavefunction to change, potentially lowering the fixed-node energy in DMC. Here, we optimize the orbitals starting from an RHF guess.

Resources: Ethanol OptOrb Test