Dear Mateusz,
The MEASURE_LOCAL_AT function is not at all optimal. This is however the cost of being generic…
For the nearest neighbors correlations you could actually use the MEASURE_LOCAL with a bond operator. This will measure on all bonds in the lattice definition.
Best, Michele
-- ETH Zurich Dr. Michele Dolfi Institute for Theoretical Physics HIT G 32.4 Wolfgang-Pauli-Str. 27 8093 Zurich Switzerland
dolfim@phys.ethz.ch www.itp.phys.ethz.ch
+41 44 633 78 56 phone +41 44 633 11 15 fax
On 14 Jan 2017, at 09:05, Mateusz Łącki mateusz.lacki@gmail.com wrote:
Dear All, I am trying to compute properties of a quantum ising model in the transverse field. I want to measure local magnetization (both transverse and along the field), and nearest neighbor correlations Sx(i) Sx(i+1) and Sz(i) Sz(i+1) for each two nearest neighbours. Later I plan on adding additional terms, but below I present the minimum model representing the problems.
For longer lattices however over 90% cpu time (tens of minutes, hours) is spent in measurement of the correlation functions.
Am I doing something wrong?
Best, Mateusz Łącki
My input file is as follows:
LATTICE="open chain lattice" MODEL=“spin"
J=1 SWEEPS=10 chkp_each=10 deleteafteruse=0 MEASURE_LOCAL[Local magnetization X]=Sx MEASURE_LOCAL[Local magnetization Z]=Sz
MEASURE_LOCAL_AT[SzSz] = "Sz:Sz|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “
MEASURE_LOCAL_AT[SpSp] = "Splus:Splus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “
MEASURE_LOCAL_AT[SmSp] = "Sminus:Splus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “
MEASURE_LOCAL_AT[SpSm] = "Splus:Sminus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) “
MEASURE_LOCAL_AT[SmSm] = "Sminus:Sminus|(0, 1),(1, 2),(2, 3),(3, 4),(4, 5),(5, 6),(6, 7),(7, 8),(8, 9),(9, 10),(10, 11),(11, 12),(12, 13),(13, 14),(14, 15),(15, 16),(16, 17),(17, 18),(18, 19),(19, 20),(20, 21),(21, 22),(22, 23),(23, 24),(24, 25),(25, 26),(26, 27),(27, 28),(28, 29),(29, 30),(30, 31),(31, 32),(32, 33),(33, 34),(34, 35),(35, 36),(36, 37),(37, 38),(38, 39),(39, 40),(40, 41),(41, 42),(42, 43),(43, 44),(44, 45),(45, 46),(46, 47),(47, 48),(48, 49),(49, 50),(50, 51),(51, 52),(52, 53),(53, 54),(54, 55),(55, 56),(56, 57),(57, 58),(58, 59),(59, 60),(60, 61),(61, 62),(62, 63),(63, 64),(64, 65),(65, 66),(66, 67),(67, 68),(68, 69),(69, 70),(70, 71),(71, 72),(72, 73),(73, 74),(74, 75),(75, 76),(76, 77),(77, 78),(78, 79),(79, 80),(80, 81),(81, 82),(82, 83),(83, 84),(84, 85),(85, 86),(86, 87),(87, 88),(88, 89),(89, 90),(90, 91),(91, 92),(92, 93),(93, 94),(94, 95),(95, 96),(96, 97),(97, 98),(98, 99),(99, 100),(100, 101),(101, 102),(102, 103),(103, 104),(104, 105),(105, 106),(106, 107),(107, 108),(108, 109),(109, 110),(110, 111),(111, 112),(112, 113),(113, 114),(114, 115),(115, 116),(116, 117),(117, 118),(118, 119),(119, 120),(120, 121),(121, 122),(122, 123),(123, 124),(124, 125),(125, 126),(126, 127) " L=128; MAXSTATES=200; NUMBER_EIGENVALUES=1;
{h=1;}
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