Hello everyone,

I have a question regarding the ground state optimization in CPCM solvent model (acetone and toluene). Based on the following input, there is an imaginary frequency mostly related to the Boron and Fluorine atoms. I also used a different grid and smaller basis set (6-31G*), but there is still an imaginary frequency. I would appreciate it if you have any suggestions for this issue.

$molecule

0 1

C 2.7200343398 -0.5442187873 -0.9227170176

C 1.2520019676 -0.6846000582 -0.7228589964

C 0.5104592957 -1.3675387249 -1.6611317225

C -0.8823631026 -1.4698819173 -1.5012575241

C -1.5316549640 -0.8505654161 -0.4472884097

C -0.7798290535 -0.2527546328 0.6090802766

C 0.6337333168 -0.1453402398 0.4475033074

C -1.3621598827 0.1825700445 1.8294805008

C -0.5907263846 0.7471659753 2.8144044484

C 0.8029652695 0.9071220605 2.6305818174

C 1.4026604847 0.4637265594 1.4784612421

C -2.9814944582 -1.1014365850 -0.5776928817

C -3.0827381975 -2.3870900917 -1.3920411669

C -1.8634571281 -2.2442205408 -2.3411230133

C -4.0227409274 -0.2917480265 -0.2536748486

C -2.9626036621 -3.6464136140 -0.5266741492

C -3.9904047126 1.1581064930 0.0758328949

C -5.3039848987 1.5959757376 0.3426322606

C -6.2143031649 0.4567395383 0.1890417190

C -5.4614030276 -0.6692619423 -0.2098067855

C -2.9598148617 2.0985973469 0.0134214218

C -3.2371464247 3.4368817376 0.2915168133

C -4.5322173198 3.8509704289 0.6118570736

C -5.5793503764 2.9308702342 0.6240961804

C -7.5909065901 0.3809373226 0.3738761906

C -8.2341861255 -0.8374902486 0.1601911170

C -7.4985852743 -1.9614257984 -0.2201648559

C -6.1160383129 -1.8890030038 -0.3975908123

C 3.2142782908 0.6038542436 -1.5486738832

C 3.5755552030 -1.5611208460 -0.4898766149

C 2.5544407336 1.7702452517 -2.0436778878

C 3.5575858945 2.5828762555 -2.5564863778

C 4.7929999626 1.9277780336 -2.3774544620

N 4.5817109741 0.7500183184 -1.7744786626

N 4.9497921866 -1.4614601783 -0.7008549656

C 5.5426709350 -2.5467552153 -0.1860359403

C 4.5605439106 -3.3834628067 0.3825188304

C 3.3204570384 -2.7835209335 0.2044230441

C 7.0164613675 -2.7551645702 -0.2475702953

C 6.1533393013 2.3934772885 -2.7676653892

H 1.0074357822 -1.8239884374 -2.5195735528

H -2.4341607689 0.0565894156 1.9771015968

H -1.0545770568 1.0755047839 3.7458177944

H 1.4043629803 1.3693491788 3.4147942978

H 2.4814498885 0.5634271732 1.3482977417

H -4.0159190997 -2.4119180126 -1.9686605913

H -2.1452364591 -1.6733439453 -3.2412402485

H -1.4631854340 -3.2137131222 -2.6738447028

H -3.0127255562 -4.5521645272 -1.1503170659

H -3.7643152243 -3.6996528020 0.2244337250

H -2.0018169383 -3.6544932989 0.0123910090

H -1.9465368053 1.8101759898 -0.2585242827

H -2.4285449273 4.1686307341 0.2500301707

H -4.7288389081 4.9021573869 0.8299374807

H -6.6005783005 3.2558893301 0.8320608848

H -8.1592520868 1.2592398250 0.6857511296

H -9.3138864250 -0.9160788019 0.2988563505

H -8.0077760213 -2.9144589749 -0.3735906300

H -5.5739276013 -2.7921352425 -0.6697631230

C 1.0954533105 2.1057815544 -2.0217987085

H 3.4280423161 3.5590148239 -3.0185018169

H 4.7542813919 -4.3320680966 0.8780369271

C 2.0146546714 -3.3371435269 0.6834849890

H 7.3557777144 -2.7388845703 -1.2933142754

H 7.5361808431 -1.9339261160 0.2664558515

H 7.2922746651 -3.7112613992 0.2138638213

H 6.1014218470 3.3804065276 -3.2436950599

H 6.8043756468 2.4432179243 -1.8831837752

H 6.6146381014 1.6755953271 -3.4610486594

B 5.6756089483 -0.2796778967 -1.3935538334

F 6.5931587937 0.3040983443 -0.5042387079

F 6.3419193572 -0.7281844984 -2.5445507621

H 0.9227374304 3.0603813512 -2.5368747511

H 0.7208732627 2.1997602441 -0.9907523450

H 0.4882021515 1.3319281241 -2.5131261632

H 2.1864934910 -4.2575714501 1.2578348527

H 1.4819931033 -2.6228302870 1.3285278644

H 1.3406544941 -3.5750251250 -0.1527527085

$end

$rem

JOBTYPE = OPT

BASIS = cc-pVDZ

EXCHANGE = wB97X-D

GEOM_OPT_MAX_CYCLES = 5000

MAX_SCF_CYCLES = 5000

GUI = 2

SYM_IGNORE = TRUE

SOLVENT_METHOD = pcm

xc_grid = 000075000302

RPA = 0

$end

$pcm

Theory CPCM

Method SWIG

Solver Inversion

Radii Bondi

$end

$solvent

Dielectric 20.7

$end

@@@

$molecule

read

$end

$rem

JOBTYPE = FREQ

BASIS = cc-PVDZ

EXCHANGE = wB97X-D

GEOM_OPT_MAX_CYCLES = 2000

GUI = 2

MAX_SCF_CYCLES = 2000

SYM_IGNORE = TRUE

xc_grid = 000075000302

RPA = 0

SOLVENT_METHOD = pcm

$end

$pcm

Theory CPCM

Method SWIG

Solver Inversion

Radii Bondi

$end

$solvent

Dielectric 20.7

$end

Best wishes,