##master-page:HelpTemplate ##master-date:Unknown-Date #format wiki #language en #Please change following line to BDF module name = Xuanyuan = <> {{{ Xuanyuan is used to calculate one electron and two electron integrals. It is named after Chinese ancestor Xuanyuan Huangdi. }}} == General keywords == === Direct === Ask for integral direct calculations. It is default now but may be turned off by the keyword '''Saorb''' in Compass. === Nondirect === When the Skeleton Fock matrix is used, ask for non-direct calculation for Fock matrix. The integrals, such as two-electron repulsive integrals, 3-center RI integrals are calculated saved. If '''Saorb''' is used in COMPASS, nondirect is the default. === Skipint === This keyword only works with direct-SCF and the '''LSSCF''' module. It asks for skip 2-electron K2 integrals used in Schwartz prescreening. The K2 integrals will be calculated in LSSCF. === Maxmem === Set maximum memory used in the integral calculation. This keyword works with '''Saorb''' in COMPASS. The unit can be MW and GW, i.e. Mega Words and Giga Words Examples: {{{ $xuanyuan Maxmem 512MW $end }}} === RSOMEGA / RS === Range separation ERIs required. RS is a synonym for RSOMEGA. No default value. Suggested value: 0.33. Examples: {{{ $xuanyuan Rsomega 0.33 $end }}} === Heff === {{{#!wiki Heff is a keyword to turn on scalar relativistic effects using sf-X2C (Heff=3) by default Other options for Heff are 0, nonrelativistic, including the cases of scalar ECP and SOECP 1, sf-ZORA 2, sf-IORA 3/4, sf-X2C 5, sf-X2C+so-DKH3 (spin-free) 21, sf-X2C 22, sf-X2C with atom-block-diagonal X and full R (sf-X2C-aXR) [ZouLiu2020] 23, sf-X2C with atom-block-diagonal unitary transformation (sf-X2C-aU) [ZouLiu2020] Among these relativistic Hamiltonians, 21, 22, and 23 have analytic gradients, hessians, and some one-electron properties (Mossbauer spectroscopy related properties at present in [[scf]]). }}} Example: {{{ $xuanyuan heff 3 $end }}} === Hsoc === '''Hsoc''' is a keyword to turn on soc integral calculations in post-SCF steps. Default option for hsoc is 0 (only 1e-soc int). The recommended option is '''2''' (so1e+somf2e). In the case of ECP (including mixed ECP, SOECP, and all-electron N.R. basis sets), only 10 (BP so-1e) is acceptable, i.e. SOECP integrals for SOECP atoms whereas effective nuclear charges for ECP and all-electron atoms. Other options are used in soint_util/somf2e.F90 for choosing different combinations of so1e and mean-feild so2e (SOMF) operators. 0 so-1e 1 so-1e + somf (two-electron spin-orbit interaction is included via an effective fock operator) '''2 so1e + somf-1c''' (one-center approximation to two-electron integrals) 3 so-1e + somf-1c / no soo (turn off spin-other-orbit contributions) 4 so-1e + somf-1c / no soo + WSO_XC (use dft xc functional as soo part) 5 so-1e + somf-1c / no soo + WSO_XC(-2x: following Neese's paper scale dft part by -2 to mimic soo part) These options plus 10 gives the operators in BP approximations. In practice, hsoc=1 is the most accurate, and hsoc=2 is preferred for large molecules. Note if heff=5, then the one-electron part will be calculated in xuanyuan and stored in disc for so-DKH3 type one-electron spin-orbit term. The accuracy of such an operator requires further tests. Examples: {{{ $xuanyuan heff 3 hsoc 2 $end }}} === Nuclear === {{{#!wiki '''Nuclear''' defines the nuclear charge distribution used in the V and pVp integrals in all-electron relativistic calculations, which can be -1 for point charge model (debug only), 0 for point charge model (default), 1 for finite nucleus model by an s-type Gaussian function, and other finite nucleus models (N.Y.I.). In the case of contracted Gaussian basis sets with a finite nucleus model (e.g. '''ANO-R''' and '''ANO-R'''-''n'', ''n'' = 0, 1, 2, 3), 1 must be used. For Za < 110, the nuclear charge radii are taken from Ref.[Visscher1997] (in a.u). For Za ≥ 110, the nuclear charge radius is 0.57 + 0.836 * A^1/3^ (in fm), where the isotope mass number A is estimated by Za according to the relationship A(Za) = 0.004467 * Za^2^ + 2.163 * Za - 1.168. See Appendix A in Ref.[Andrae2000] and Ref.[Andrae2002]. }}} '''NOTE''': the finite nucleus model has been implemented only in scalar calculations at present, but will be used in SOC calculations soon. === Cholesky === {{{#!wiki The following line contains a string and a float number. Set method and threshold of ERI Cholesky decomposition. S-CD for standard CD. 1c-CD for one center Cholesky decomposition. }}} Examples: {{{ $xuanyuan Cholesky S-CD 1.d-5 $end }}} == Expert keywords == === NoCheck === {{{#!wiki For Heff=21 only: check inverse variational collapse (IVC; see Ref.[Liu2007]). Stop (0; default) or not (1) in the case of IVC. IVC may lead to numerical instability, which may be serious in geometry optimization. }}} === NRDebug === {{{#!wiki In relativistic calculations, use a C-light of 10^8 to reproduce non-relativistic results (for debug only). }}} === Keyword3 === {{{#!wiki xxx }}} === Keyword4 === {{{#!wiki xxx }}} = Depend Files = ||Filename ||Description ||Format || Position || Input/output || || $BDFTASK.chkfil || Global variables || Binary || WORKDIR || Input/Output || || $BDFTASK.int1e || AO One-electron integrals. || Binary || TMPDIR || Output || || $BDFTASK.int2e || Two-electron integrals. || Binary || TMPDIR || Output || || $BDFTASK.intscr || Scratch file to save two-electon integrals. Only used in symmetry-adapted integrals('''Saorb''') || Binary || TMPDIR || Output || || $BDFTASK.k2int || K2 loop integrals. Used in direct-SCF. || Binary || TMPDIR || Output || || $BDFTASK.int2ee || Range-seprated 2e integrals used in RS hybrid functional || Binary || TMPDIR || Output || = Examples = N.A. = References = * [Andrae2000] D. Andrae, Phys. Rep. 336, 413 (2000). * [Andrae2002] D. Andrae, Nuclear charge density distributions in quantum chemistry, in Relativistic Electronic Structure Theory, Part 1: Fundamentals, P. Schwerdtfeger Ed., Theoretical and Computational Chemistry, Vol. 11, Elsevier, 2002. * [Liu2007] W. Liu and W. Kutzelnigg, J. Chem. Phys. 126, 114107 (2007). * [Visscher1997] L. Visscher and K. G. Dyall, At. Data and Nucl. Data Tables 67, 207 (1997). * [ZouLiu2020] W. Zou, G. Guo, B. Suo, and W. Liu, J. Chem. Theory Comput. 16, 1541 (2020).