SCF

Contents

SCF
Depend Files
Examples
1. How to perform a direct DFT calculation with B3LYP functional?
2. How to read molecular orbital as initial guess orbital or restart SCF calculation?

HF/DFT.

General keywords

RHF/UHF/ROHF

Must input one of them if Hartree-Fock calculation is required. Require for restricted/unrestricted/restricted open shell Hartree-Fock calculations.

Example:

$Scf
RHF
$end

RKS/UKS/ROKS

Must input one of them if Kohn-Sham calculation is required. Require for restricted/unrestricted/restricted open shell Kohn-Sham calculations.

Occupy

Used in RHF/RKS. Set double occupied number of each irreps. The following line is an integer array, $noccu(i),i=1,\cdots, nirreps$.

Alpha

Used in UHF/ROHF/UKS/ROKS. Set number of alpha orbitals in each irreps. The following line is an integer array, $nalpha(i),i=1,\cdots, nirreps$.

Beta

Used in UHF\/ROHF\/UKS\/ROKS. Set number of beta orbitals in each irreps. The following line is an integer array,$ nbeta(i),i=1,\cdots , nirreps$.

Charge

Charge of the state.

Spin

Spin of the state. The value is 2S+1.

keyword

DFT functional keywords

DFT

DFT functional used in Korn-Sham calculation. Commonly used functionals: SVWN5, BLYP, B3LYP, CAM-B3LYP, etc.

LSDA:
- ex_fun=1 co_fun=1
SVWN5:
- ex_fun=1 co_fun=2
PW91:
- ex_fun=3 co_fun=3
SAOP:
- ex_fun=30 co_fun=30
BLYP:
- ex_fun=4 co_fun=8
BHHLYP
- ex_fun=21 co_fun=8
B2PLYP
- ex_fun=22 co_fun=8
B3LYP
- ex_fun=20 co_fun=0
LC-BLYP
- ex_fun=104 co_fun=8
CAM-B3LYP
- alpha=0.19d0 beta=0.46d0 ex_fun=120 co_fun=0
B3PW91
- ex_fun=27 co_fun=0
PBE PBE0 VBLYP GBLYP SF5050 LC-BVWN5 LC-BLYP SAOP

RS

Alpha and beta value in CAM calculation. The following line are two float number. For example : 0.33 0.15

D3

Grimmers dispersion corrrection for DFT.

DFT grid keywords

NPTRAD

Number of radius grid points.

NPTANG

Number of angular grid points.

Grid

Set DFT grid. Support values are: Ultra Coarse, Coarse, Medium, Fine, Ultra Fine, SG1.

NoSymGrid

Do not use symmetry dependent grid. Only for debugging.

DirectGrid

Use DirectGrid. Basis set values on the grid points are calculated directly. Default: Direct SCF, use direct grid. None Direct SCF, do not use direct grid.

NoDirectGrid

Force to do not use direct grid.

NoGridSwitch

For direct SCF, DFT grid can be switched. At the beging of iteration, Ultra coase grid will be used. After energer change is little than a value, such as 1.d-4, the medium grid or user setted grid
will be used. NoGridSwitch dissiable grid switch and use default grid directly.

ThreshRho

If the numerical integral $\rho_{\mu}<threshRho$ , the basis $\chi_{\mu}$ will be neglected. The $\rho_{\mu}$ is defined as
- $\rho_{\mu}=\sum_i w_i*\chi_{\mu}(r_i)\chi_{\mu}(r_i)$
Default value: $ThreshRho=\frac{thresh\_{ene}}{maxradgrid*maxanggrid*natom}$

Coulpot

Use multipolar expansion to get coulomb potential and matrix.

Coulpotlmax

Max L value for coulomb potential multipolar expansion. Default value: 5

Coulpottol

Cutoff threshold parameter for coulomb potential multipolar expansion, more higher more accurate. Default value: 8.

SCF convergence

MAXITER

The maximum Number of SCF iteration

NODIIS

Logical control parameter. Disable DIIS.

MaxDiis

Maxim number of Diis space. Default: 8

THRENE

Convergence threshhold for energy. Default: 1.d-8.

THRDEN

Convergence threshhold for density matrix. Default: 3.d-6.

ThreshConverg

Convergence threhhold. Two float value: DeltaE DeltaD

THRDIIS

Threshold to turn on DIIS. Default: 0.15.

DIISmode

DIISmode: 
0: diisdim goes from 0 to maxdiis, then cycles to 0. And reset to 0 when diis fails. 
1: diisdim goes from 0 to maxdiis, keeps maxdiis. And throw the oldest vector (reduce diisdim) when diis fails.
Default: 0.

Vshift

Level shift value.

Damp

Damping value.

Icheck

Check Aufbau law.

IAUFBAU

Control parameter of electron occupation protocol in each SCF iteration.
IAUFBAU = 1, electron occupation obeys Aufbau principle(default);
IAUFBAU = 2, electrons complies with specific occupation pattern based on maximum occupation method(mom);
IAUFBAU = 3, electrons complies with specific occupation pattern based on maximum occupation method(mom).Update MO coefficients and reorder occupied orbitals in each iteration.  
WARNING if IAUFBAU=2 or 3 without initial guess=read (this means initial guess is bad), the result is unpredictable.

Print and output SCF orbital into Molden format

print

Print level.

iprtmo

Require to print MO coefficients. Values: 1 Only print orbital energy and occupation numbers. 2 Print all information.

Molden

Output SCF orbital into Molden format file.

Expert keywords

IfNoDeltaP

Dissable using DeltaP to update Fock matrix.

IfDeltaP

Delta P is used to update density matrix. In direct SCF calculation, delta P will be used in integral prescreening instead of P. Default: true.

Optscreen

For debugging. Set a strict threshold (thresh_rho=1.d-4) for integral prescreening directly.

Nok2Prim

Disable primative integral screenning via K2 integrals. Use (SS|SS) esitimating primative integral value and perform screening. Default: Direct SCF, use K2 primative screening.
- None Direct SCF, use (SS|SS) integral.

FixDif

Fix factor for incremental fock update. If the factor is not fixed, use the formular \begin{align*}
- fac=1-\frac{D^{n+1}-Dn}{D^{n+1}*D{n+1}} \\ F^{n+1}=Fn+fac*\delta F
\end{align*} if using fixed factor, fac=1.d0.

Jengin

Use Jengin method calculate J matrix. In debugging, not support now.

LinK

Use LinK calculate K matrix. In debugging, not support now.

Guess

Method to get initial guess orbital. The following line is a string.
- Values: Atom, Hcore, Huckel, Read. If Read is used, the old orbital will be read. The old orbital saves in a file named "inporb" in BDF_TMPDIR . It is generated by previous SCF calcualtion with the name Task.scforb.

Cutlmotail

Methods to cut long Coulomb tails of Local molecular orital. Values: -1 Do not cut tail. 1 Project a LMO into fragment with largest Lowdin population.
- 2 Similar with 1, but project a LMO into predefined group of fragments with largest Lowdin population. 3 Very stick cutoff. Project LMO to a fragment plus several atoms. The threshhold is 1.d-4.
Comment: Method 1 is prefered if fragments are well defined. We can easy reduce compuations times in post
- SCF calcualtion based on LMO because diffirent fragment interaction policy can be predefined, which will reduce ERIs need to be calculated.

CHECKLIN

Check if the basis sets is linear dependent. If diffuse basis set is used, SCF do not converge or ridiculous energy observed, it is better to check linear dependent of the basis set.

ΤΟLLIN

Tolerance of basis set linear dependent. Default value 1.d-7.

ifPair

used to excite electrons (MOM)with following keywords:
hpalpha,hpbeta
then with number of partical-hole pairs N
then with 2N lines specificate partical-hole pairs. (0 is do nothing, indexes start from 1)
eg. the molecular is has 4 irreducible representation, we want to excite electrons from orb 5,6 to 8,9 in rep 1 and 3 to 4 in rep 3 (alpha) & 7 to 8 in rep 1(beta):

ifpair
hpalpha
2
5 0 3 0
8 0 4 0
6 0 0 0
9 0 0 0
hpbeta
1
7 0 0 0
8 0 0 0

this should be combined with iaufbau=2 or 3.
WARNING: this function will not check whether partical orbital is filled or whether hole orbiltal is not filled.

pinalpha , pinbeta

specificate fix orbitals
first line specificates the number of fix orbitals
then with N lines specificate fix orbitals. (0 is do nothing, indexes start from 1)
(somewhat likes hpalpha/hpbeta input)
these keywords leads to SCF_solver from solve FC=SCE to $\tilde{F}U=UE,\tilde{F}=C^\dagger FC$

Depend Files

Filename	Description	Format

Examples

How to perform a direct DFT calculation with B3LYP functional?

$COMPASS 
Title
 Cocaine Molecule test run, CC-PVDZ
Basis
  CC-PVDZ
Geometry
  XYZ               # The molecule geometry will be read from file $BDFTASK.xyz 
End Geometry
Skeleton          # This keyword must be used.
$End

$xuanyuan
Direct              # Direct SCF.
Schwarz          # Schwarz prescreening.
$end

$scf
RKS
DFT functional
 B3LYP
Molden     # This keyword is used to output SCF orbital to molden format file.
$end

How to read molecular orbital as initial guess orbital or restart SCF calculation?

Suppose you have performed a calculation and generated aSCF orbital file in your work directory as test.scforb. Usually, this file atomically generated by SCF module. This file also can be used to restart SCF calculation via read it as initial guess orbital.

$COMPASS 
Title
 Cocaine Molecule test run, CC-PVDZ
Basis
  CC-PVDZ
Geometry
  XYZ    # The molecule geometry will be read from file $BDFTASK.xyz. 
End Geometry
Skeleton          # This keyword must be used.
$End

$xuanyuan
Direct              # Direct SCF.
Schwarz          # Schwarz prescreening.
$end

# Copy orbital file test.scforb as inporb in BDF_TMPDIR
% cp $BDF_WORKDIR/test.scforb $BDF_TMPDIR/inporb

$scf
RKS
DFT functional
 B3LYP
Guess       # Read orbital as  initial guess orbital
 Read
Molden     # This keyword is used to output SCF orbital to molden format file.
$end

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