RESP: module for response properties based on HF and DFT
Contents
- RESP: module for response properties based on HF and DFT
- Quick guides by examples
- Some caveats before using this module
Keywords for general information
IPRT
Print level, >1 gives more information, >2 give more information about integral evaluations.
NPRT
CHCK
Check the interface with several external packages.
CTHRD
Keyworks for processing excited-state information
METHOD
=1, ground state gradients; =2, excited-state calculations which will load TD-DFT output.
NFILES
Linked with istore value in TD-DFT input for loading output.
Keyword for geometric derivatives
GEOM: NORDER
GEOM enables geometric derivatives, NORDER=1, gradient and fo-NACMEs; =2, hessian (not implemented yet.)
Keywords for linear response calculations
LINE
Enable linear response
REDUCED
Solve the response equation in its reduced form [(A-B)(A+B)-w2](X+Y)=Rvo+Rov (not preferred).
POLA: AOPER, BOPER, BFREQ
Polarizabiity: <<A;B>>(wB), where the operators A and B can be dipole (DIP), quadruple (QUA), SOC (HSO), EFG.
Keywords for quadratic response calculations
QUAD
Enable quadratic response function (QRF) calculations
HYPE: AOPER, BOPER, BFREQ, COPER, CFREQ
Hyperpolarizability: <<A;B,C>>(wB,wC)
SINGLE:STATES
Single residue of QRF, STATES can be used to specify the number of states followed by a detailed specification via the triple (ifile,isym,istate).
DOUBLE: PAIRS
Double residue of QRF, PAIRS can be used to specify the number of pairs followed by a detailed specification via two triples (ifile,isym,istate,jfile,isym,jstate).
FNAC
First-order nonadiabatic couplings
NORESP
Neglect the response part of transition density matrix in DOUBLE and FNAC calculations (recommended)
Keywords for finite difference calculations
FDIF
Enable finite difference calculations
STEP
followed by a real number for the step size, default 0.001 [unit].
BOHR
The default unit is angstrom, to use bohr. This keyword must be specified.
IGNORE
Ignore the recomputation of excitation energies for check consistency.
Quick guides by examples
The following examples give the minimal inputs for starting response calculations (Input files and benchmark results can be found in bdf-pkg/tests/input/resp2014):
Response properties based on linear and quadratic response functions
Alternative of TD-DFT: particle-particle TDA (pp-TDA) based properties
Some caveats before using this module
dft
1. Thresholds in dft_prescreen.F90 have been set very tight.
2. Keyword ixcfun in SCF allows to use original XC library (default) or XCFun lib (=1) by Ulf Ekström [http://www.admol.org/xcfun] in dft and tddft.
scf
1. Tight convergence on density matrix is required (10-14).
2. sgnfix: fix adjacent sign of MOs during SCF iterations
2. iaufbau=3: fix ordering and sign with respect to the initial MOs.
tddft
1. Tight convergence on eigenvectors (10-8).
2. Keyword lefteig for storing left eigenvectors in TD-DFT
3. Keyword istore speficify the file number of TD-DFT calculations