Problem with tuning omega in LRC-wPBE

Questions
#1

Hi developers and users,
During the omega (ω) tuning process for a given molecule, input files were prepared for the neutral, cationic, and anionic states, with an initial omega value of 300. After executing the job using the ‘OptOmegaIPEA.pl’ script, multiple input (.in) and output (.out) files were generated, each corresponding to same omega values.

Upon reviewing the “optomega file”,a lot of values and the optimal omega was determined to be 100.01, significantly lower than the initially assigned value of 300.
The input is as follows
N.in
$molecule
0 1
C 3.4692763175390144 -0.8747762505392289 0.2887879113176441
C 2.7241748910857067 -2.0610453846291814 0.3665005225560375
C 1.3377472813147677 -2.0289405741401931 0.3076496161093945
C 2.8527018512811830 0.3610567219882468 0.1440989257345488
C 1.4588239671483865 0.3830435751349681 0.0741825542216589
C 0.6934282113543170 -0.7986405068795038 0.1622265180385100
C -0.7070764570050641 1.0049118750988739 -0.0445268788370491
C -0.6961525374407573 -0.3997137615613204 0.0855092583511324
C -1.9038165079460274 -1.1005285530019491 0.1031893552728273
C -3.0940239787634201 -0.3956916417451283 -0.0120812619409538
C -1.8986779700227370 1.7204281726502442 -0.1726380102991579
C -3.0858488677101565 1.0002931397751547 -0.1520975239646462
H 4.5539041072531061 -0.9212886504425670 0.3457127203128101
H 3.2392564563652466 -3.0112344243525615 0.4786346187269981
H 0.7611968386102280 -2.9482187777248576 0.3768159381917063
H 3.4353297744604099 1.2762505040041954 0.0937192102534364
H -1.9112930483010080 -2.1832453184158158 0.2028454128715945
H -4.0414740018173685 -0.9275783635041150 0.0009943467575237
H -1.8994126628178278 2.8001074756199889 -0.2904137998461905
H -4.0288820351895760 1.5322621324524099 -0.2496901482165260
N 0.6024939713294349 1.4707647062164562 -0.0507033764973130
C 0.9979601369991469 2.8259876093364462 -0.1647515787500540
C 0.5801131228003912 3.7563971510757206 0.7874019833269067
H -0.0364705721236071 3.4263346167296329 1.6193253708836275
C 0.9627170585057938 5.0889868475500863 0.6670735864271023
H 0.6332705319286811 5.8116492682621805 1.4091623489195766
C 1.7764547140569185 5.4928326977882218 -0.3888680163942174
H 2.0800417445642423 6.5326967623770047 -0.4762495663275934
C 2.1999125464850695 4.5597799583898802 -1.3324723383205601
H 2.8309026825172645 4.8700469017982151 -2.1613594880603104
C 1.8051302581422444 3.2293269409832064 -1.2290106539526910
H 2.1118021753959897 2.4974151497052781 -1.9716275568657788
$end

$rem
jobtype sp
METHOD LRC-wPBE
BASIS 6-31+G(d,p)
lrc_dft true
Omega 300
SCF_FINAL_PRINT 1
GEN_SCFMAN FALSE
print_input true
THRESH 12
COMBINE_K TRUE
mem_static 4000
MEM_TOTAL 32000
SYMMETRY FALSE
SYM_IGNORE TRUE
$end

P.in
$molecule
1 2
C 3.4692763175390144 -0.8747762505392289 0.2887879113176441
C 2.7241748910857067 -2.0610453846291814 0.3665005225560375
C 1.3377472813147677 -2.0289405741401931 0.3076496161093945
C 2.8527018512811830 0.3610567219882468 0.1440989257345488
C 1.4588239671483865 0.3830435751349681 0.0741825542216589
C 0.6934282113543170 -0.7986405068795038 0.1622265180385100
C -0.7070764570050641 1.0049118750988739 -0.0445268788370491
C -0.6961525374407573 -0.3997137615613204 0.0855092583511324
C -1.9038165079460274 -1.1005285530019491 0.1031893552728273
C -3.0940239787634201 -0.3956916417451283 -0.0120812619409538
C -1.8986779700227370 1.7204281726502442 -0.1726380102991579
C -3.0858488677101565 1.0002931397751547 -0.1520975239646462
H 4.5539041072531061 -0.9212886504425670 0.3457127203128101
H 3.2392564563652466 -3.0112344243525615 0.4786346187269981
H 0.7611968386102280 -2.9482187777248576 0.3768159381917063
H 3.4353297744604099 1.2762505040041954 0.0937192102534364
H -1.9112930483010080 -2.1832453184158158 0.2028454128715945
H -4.0414740018173685 -0.9275783635041150 0.0009943467575237
H -1.8994126628178278 2.8001074756199889 -0.2904137998461905
H -4.0288820351895760 1.5322621324524099 -0.2496901482165260
N 0.6024939713294349 1.4707647062164562 -0.0507033764973130
C 0.9979601369991469 2.8259876093364462 -0.1647515787500540
C 0.5801131228003912 3.7563971510757206 0.7874019833269067
H -0.0364705721236071 3.4263346167296329 1.6193253708836275
C 0.9627170585057938 5.0889868475500863 0.6670735864271023
H 0.6332705319286811 5.8116492682621805 1.4091623489195766
C 1.7764547140569185 5.4928326977882218 -0.3888680163942174
H 2.0800417445642423 6.5326967623770047 -0.4762495663275934
C 2.1999125464850695 4.5597799583898802 -1.3324723383205601
H 2.8309026825172645 4.8700469017982151 -2.1613594880603104
C 1.8051302581422444 3.2293269409832064 -1.2290106539526910
H 2.1118021753959897 2.4974151497052781 -1.9716275568657788
$end

$rem
jobtype sp
METHOD LRC-wPBE
BASIS 6-31+G(d,p)
lrc_dft true
Omega 300
SCF_FINAL_PRINT 1
GEN_SCFMAN FALSE
print_input true
THRESH 12
COMBINE_K TRUE
mem_static 4000
MEM_TOTAL 32000
SYMMETRY FALSE
SYM_IGNORE TRUE
$end

M.in
$molecule
-1 2
C 3.4692763175390144 -0.8747762505392289 0.2887879113176441
C 2.7241748910857067 -2.0610453846291814 0.3665005225560375
C 1.3377472813147677 -2.0289405741401931 0.3076496161093945
C 2.8527018512811830 0.3610567219882468 0.1440989257345488
C 1.4588239671483865 0.3830435751349681 0.0741825542216589
C 0.6934282113543170 -0.7986405068795038 0.1622265180385100
C -0.7070764570050641 1.0049118750988739 -0.0445268788370491
C -0.6961525374407573 -0.3997137615613204 0.0855092583511324
C -1.9038165079460274 -1.1005285530019491 0.1031893552728273
C -3.0940239787634201 -0.3956916417451283 -0.0120812619409538
C -1.8986779700227370 1.7204281726502442 -0.1726380102991579
C -3.0858488677101565 1.0002931397751547 -0.1520975239646462
H 4.5539041072531061 -0.9212886504425670 0.3457127203128101
H 3.2392564563652466 -3.0112344243525615 0.4786346187269981
H 0.7611968386102280 -2.9482187777248576 0.3768159381917063
H 3.4353297744604099 1.2762505040041954 0.0937192102534364
H -1.9112930483010080 -2.1832453184158158 0.2028454128715945
H -4.0414740018173685 -0.9275783635041150 0.0009943467575237
H -1.8994126628178278 2.8001074756199889 -0.2904137998461905
H -4.0288820351895760 1.5322621324524099 -0.2496901482165260
N 0.6024939713294349 1.4707647062164562 -0.0507033764973130
C 0.9979601369991469 2.8259876093364462 -0.1647515787500540
C 0.5801131228003912 3.7563971510757206 0.7874019833269067
H -0.0364705721236071 3.4263346167296329 1.6193253708836275
C 0.9627170585057938 5.0889868475500863 0.6670735864271023
H 0.6332705319286811 5.8116492682621805 1.4091623489195766
C 1.7764547140569185 5.4928326977882218 -0.3888680163942174
H 2.0800417445642423 6.5326967623770047 -0.4762495663275934
C 2.1999125464850695 4.5597799583898802 -1.3324723383205601
H 2.8309026825172645 4.8700469017982151 -2.1613594880603104
C 1.8051302581422444 3.2293269409832064 -1.2290106539526910
H 2.1118021753959897 2.4974151497052781 -1.9716275568657788
$end

$rem
jobtype sp
METHOD LRC-wPBE
BASIS 6-31+G(d,p)
lrc_dft true
Omega 300
SCF_FINAL_PRINT 1
GEN_SCFMAN FALSE
print_input true
THRESH 12
COMBINE_K TRUE
mem_static 4000
MEM_TOTAL 32000
SYMMETRY FALSE
SYM_IGNORE TRUE
$end

The Optomega file generated was as follows:
347
500
253
194
158
136
122
114
109
105
103
102
101
101
100
100
100
100
100
100
100
100
100
100
gamma optimal:100.010100245387

Thank you for your time.

2 Likes
#2

Does changing the initial conditions and re-running these calculations give a different optimal omega? Not sure but maybe doing this exercise might shed more light on the issue.

#3

Note that the script has hard-coded upper and lower bounds for omega, see the line

$optGamma=&Minimum(100,500,800);

In addition, it implements a rather crude line search that uses a large step size that sometimes gives us trouble. When in doubt, verify it yourself using a 1-d scan over omega. Alternatively, you can try GDD tuning as described in the manual and recently highlighted in this paper:
https://doi.org/10.1021/acs.jpclett.5c00086