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.

Schwarz

Used with direct, ask for Schwarz equality prescreening.

Examples:

$xuanyuan
Direct
Schwarz
$end

Maxmem

Set maximum memory used in integral calculation. Unit can be MW and GW, i.e. Mega Words and Giga Words

Examples:

$xuanyuan
Maxmem
  512MW 
$end

RS

• Range separation ERIs required. No default value. Suggested value: 0.33.

Examples:

$xuanyuan
Rs
 0.33
$end

Scalar & Heff

Scalar is a keyword to turn on scalar relativistic effects using sf-X2C (Heff=3) by default.

Other options for Heff are (0, nonrelativistic; 1, sf-ZORA; 2, sf-IORA; 3/4, sf-X2C; 5, sf-X2C+so-DKH3 (spin-free))

Examples:

$xuanyuan
scalar
heff
3
$end

Socint & Hsoc

Socint is a keyword to turn on soc integral calculations in post-SCF steps. Default option for hsoc is 0 (only 1e-soc int).

Other options are used in soint_util/somf2e.F90 for choosing different combinations of so1e and so2e operators.

0 so-1e

1 so-1e + somf (two-electron spin-orbit interaction is included via an effective fock operator)

2 so-1e + somf-1c (one-center approximation)

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 operator requires further tests.

Examples:

$xuanyuan
scalar
heff
3
socint
hsoc
2
$end

Cholesky

• 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

Keyword3

xxx

Keyword4

xxx

Depend Files

Examples